diff --git a/cc/google/fhir/BUILD b/cc/google/fhir/BUILD
index 6933d55c7..417ed9250 100644
--- a/cc/google/fhir/BUILD
+++ b/cc/google/fhir/BUILD
@@ -85,12 +85,15 @@ cc_library(
     deps = [
         ":annotations",
         ":core_resource_registry",
-        ":type_macros",
+        ":proto_util",
         ":util",
+        "//cc/google/fhir/status",
         "//cc/google/fhir/status:statusor",
+        "@com_google_absl//absl/memory",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",
         "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/types:optional",
         "@com_google_protobuf//:protobuf",
         "@com_googlesource_code_re2//:re2",
     ],
@@ -327,6 +330,7 @@ cc_library(
         ":extensions",
         ":fhir_types",
         ":json_format_results",
+        ":json_util",
         ":primitive_handler",
         ":primitive_wrapper",
         ":proto_util",
@@ -340,6 +344,7 @@ cc_library(
         "//cc/google/fhir/status",
         "//cc/google/fhir/status:statusor",
         "//proto/google/fhir/proto:annotations_cc_proto",
+        "@com_google_absl//absl/base:core_headers",
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/memory",
         "@com_google_absl//absl/status",
@@ -480,10 +485,12 @@ cc_library(
     hdrs = ["json_util.h"],
     strip_include_prefix = "//cc/",
     deps = [
+        ":annotations",
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",
         "@com_google_absl//absl/strings",
+        "@com_google_protobuf//:protobuf",
     ],
 )
 
@@ -521,10 +528,9 @@ cc_test(
     deps = [
         ":json_util",
         "//cc/google/fhir/status",
-        "//cc/google/fhir/status:statusor",
-        "@com_google_absl//absl/status",
-        "@com_google_absl//absl/status:statusor",
-        "@com_google_absl//absl/strings",
+        "//proto/google/fhir/proto/r4/core:datatypes_cc_proto",
+        "//proto/google/fhir/proto/r4/core/resources:observation_cc_proto",
+        "//proto/google/fhir/proto/r4/core/resources:patient_cc_proto",
         "@com_google_googletest//:gtest_main",
     ],
 )
diff --git a/cc/google/fhir/fhir_path/BUILD b/cc/google/fhir/fhir_path/BUILD
index 02061a1b7..bd54454b8 100644
--- a/cc/google/fhir/fhir_path/BUILD
+++ b/cc/google/fhir/fhir_path/BUILD
@@ -82,6 +82,7 @@ cc_library(
         ":fhir_path",
         "//cc/google/fhir:annotations",
         "//cc/google/fhir:error_reporter",
+        "//cc/google/fhir:json_util",
         "//cc/google/fhir:primitive_handler",
         "//cc/google/fhir:proto_util",
         "//cc/google/fhir:util",
@@ -89,12 +90,9 @@ cc_library(
         "//cc/google/fhir/status:statusor",
         "//proto/google/fhir/proto:annotations_cc_proto",
         "@com_google_absl//absl/base:core_headers",
-        "@com_google_absl//absl/memory",
-        "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/synchronization",
-        "@com_google_absl//absl/types:optional",
         "@com_google_protobuf//:protobuf",
     ],
 )
@@ -181,9 +179,10 @@ cc_library(
     strip_include_prefix = "//cc/",
     visibility = [":__pkg__"],
     deps = [
+        "//cc/google/fhir:annotations",
+        "//cc/google/fhir:json_util",
         "//cc/google/fhir:references",
         "//cc/google/fhir:util",
-        "//cc/google/fhir/status",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/strings:str_format",
diff --git a/cc/google/fhir/fhir_path/fhir_path_validation.cc b/cc/google/fhir/fhir_path/fhir_path_validation.cc
index 2f989e8b2..9d27ab9e5 100644
--- a/cc/google/fhir/fhir_path/fhir_path_validation.cc
+++ b/cc/google/fhir/fhir_path/fhir_path_validation.cc
@@ -29,6 +29,7 @@
 #include "google/fhir/annotations.h"
 #include "google/fhir/error_reporter.h"
 #include "google/fhir/fhir_path/fhir_path.h"
+#include "google/fhir/json_util.h"
 #include "google/fhir/primitive_handler.h"
 #include "google/fhir/proto_util.h"
 #include "google/fhir/status/status.h"
@@ -320,10 +321,11 @@ absl::Status ValidateConstraint(const internal::WorkspaceMessage& message,
 }
 
 std::string PathTerm(const Message& message, const FieldDescriptor* field) {
-  return IsContainedResource(message) ||
-                 IsChoiceTypeContainer(message.GetDescriptor())
-             ? absl::StrCat("ofType(", field->message_type()->name(), ")")
-             : field->json_name();
+  if (IsContainedResource(message) ||
+      IsChoiceTypeContainer(message.GetDescriptor())) {
+    return absl::StrCat("ofType(", field->message_type()->name(), ")");
+  }
+  return FhirJsonName(field);
 }
 
 namespace {
diff --git a/cc/google/fhir/fhir_path/utils.cc b/cc/google/fhir/fhir_path/utils.cc
index 07cfce522..802d856bd 100644
--- a/cc/google/fhir/fhir_path/utils.cc
+++ b/cc/google/fhir/fhir_path/utils.cc
@@ -15,9 +15,12 @@
 #include "google/fhir/fhir_path/utils.h"
 
 #include "google/protobuf/any.pb.h"
+#include "google/protobuf/descriptor.h"
 #include "absl/status/status.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
+#include "google/fhir/annotations.h"
+#include "google/fhir/json_util.h"
 #include "google/fhir/references.h"
 #include "google/fhir/util.h"
 
@@ -27,8 +30,8 @@ namespace fhir_path {
 namespace internal {
 
 using ::absl::NotFoundError;
-using ::google::protobuf::FieldDescriptor;
 using ::google::protobuf::Descriptor;
+using ::google::protobuf::FieldDescriptor;
 using ::google::protobuf::Message;
 using ::google::protobuf::Reflection;
 
@@ -68,15 +71,14 @@ absl::Status OneofMessageFromContainer(const Message& container_message,
 
 namespace {
 
-// Returns true if `message` is a Reference and field_descriptor is a field
-// within `message` that resolves to 'reference' in FHIR.
-// Note: the json_name corresponds to fields in FHIR.
-bool IsReference(const Message& message,
-                 const google::protobuf::FieldDescriptor& field_descriptor) {
+// Returns true if `message` is a Reference and field_descriptor is the `uri`
+// field.
+bool IsReferenceUri(const Message& message,
+                    const google::protobuf::FieldDescriptor& field_descriptor) {
   return message.GetDescriptor()->options().GetExtension(
              ::google::fhir::proto::fhir_structure_definition_url) ==
              "http://hl7.org/fhir/StructureDefinition/Reference" &&
-         field_descriptor.json_name() == "reference";
+         field_descriptor.name() == "uri";
 }
 
 }  // namespace
@@ -95,7 +97,7 @@ absl::Status RetrieveField(
   // If asked to retrieve a reference, retrieve a String value with a standard
   // representation (i.e. ResourceType/id) regardless of how the reference is
   // stored in the source message.
-  if (IsReference(root, field)) {
+  if (IsReferenceUri(root, field)) {
     Message* string_message = message_factory(field.message_type());
     if (string_message == nullptr) {
       return absl::InternalError(
@@ -162,7 +164,7 @@ bool HasFieldWithJsonName(const Descriptor* descriptor,
 const FieldDescriptor* FindFieldByJsonName(const Descriptor* descriptor,
                                            absl::string_view json_name) {
   for (int i = 0; i < descriptor->field_count(); ++i) {
-    if (json_name == descriptor->field(i)->json_name()) {
+    if (json_name == FhirJsonName(descriptor->field(i))) {
       return descriptor->field(i);
     }
   }
diff --git a/cc/google/fhir/json_parser.cc b/cc/google/fhir/json_parser.cc
index e4ec370e7..dd818817b 100644
--- a/cc/google/fhir/json_parser.cc
+++ b/cc/google/fhir/json_parser.cc
@@ -17,6 +17,7 @@
 #include <ctype.h>
 
 #include <cctype>
+#include <cstdint>
 #include <iosfwd>
 #include <memory>
 #include <string>
@@ -24,12 +25,15 @@
 #include <utility>
 
 #include "google/protobuf/any.pb.h"
+#include "absl/base/attributes.h"
+#include "absl/base/const_init.h"
 #include "absl/container/flat_hash_map.h"
 #include "absl/memory/memory.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
+#include "absl/strings/string_view.h"
 #include "absl/synchronization/mutex.h"
 #include "google/fhir/annotations.h"
 #include "google/fhir/core_resource_registry.h"
@@ -39,6 +43,7 @@
 #include "google/fhir/json/json_sax_handler.h"
 #include "google/fhir/json_format.h"
 #include "google/fhir/json_format_results.h"
+#include "google/fhir/json_util.h"
 #include "google/fhir/primitive_wrapper.h"
 #include "google/fhir/r4/profiles.h"
 #include "google/fhir/references.h"
@@ -75,6 +80,7 @@ MakeFieldMap(const Descriptor* descriptor) {
       std::unordered_map<std::string, const FieldDescriptor*>>();
   for (int i = 0; i < descriptor->field_count(); i++) {
     const FieldDescriptor* field = descriptor->field(i);
+    const std::string& json_name = FhirJsonName(field);
     if (IsChoiceType(field)) {
       std::unique_ptr<
           const std::unordered_map<std::string, const FieldDescriptor*>>
@@ -85,23 +91,23 @@ MakeFieldMap(const Descriptor* descriptor) {
           // Convert primitive extension field name to field on choice type,
           // e.g., value + _boolean -> _valueBoolean for Extension.value.
           child_field_name[1] = std::toupper(child_field_name[1]);
-          (*field_map)[absl::StrCat("_", field->json_name(),
+          (*field_map)[absl::StrCat("_", json_name,
                                     child_field_name.substr(1))] = field;
         } else {
           // For non-primitive, just append them together as camelcase, e.g.,
           // value + boolean = valueBoolean
           child_field_name[0] = std::toupper(child_field_name[0]);
-          (*field_map)[absl::StrCat(field->json_name(), child_field_name)] =
-              field;
+          (*field_map)[absl::StrCat(json_name, child_field_name)] = field;
         }
       }
     } else {
-      (*field_map)[field->json_name()] = field;
+      (*field_map)[json_name] = field;
+
       if (field->type() == FieldDescriptor::TYPE_MESSAGE &&
           IsPrimitive(field->message_type())) {
         // Fhir JSON represents extensions to primitive fields as separate
         // standalone JSON objects, keyed by the "_" + field name.
-        (*field_map)["_" + field->json_name()] = field;
+        (*field_map)["_" + json_name] = field;
       }
     }
   }
diff --git a/cc/google/fhir/json_printer.cc b/cc/google/fhir/json_printer.cc
index aabf386e8..4523af5e0 100644
--- a/cc/google/fhir/json_printer.cc
+++ b/cc/google/fhir/json_printer.cc
@@ -36,6 +36,7 @@
 #include "google/fhir/extensions.h"
 #include "google/fhir/fhir_types.h"
 #include "google/fhir/json_format.h"
+#include "google/fhir/json_util.h"
 #include "google/fhir/primitive_handler.h"
 #include "google/fhir/proto_util.h"
 #include "google/fhir/r4/codeable_concepts.h"
@@ -269,7 +270,7 @@ class Printer {
       // to query all possible choice types in a single query.
       if (IsChoiceType(field) && json_format_ == kFormatPure) {
         FHIR_RETURN_IF_ERROR(PrintChoiceTypeField(
-            reflection->GetMessage(proto, field), field->json_name()));
+            reflection->GetMessage(proto, field), FhirJsonName(field)));
       } else {
         FHIR_RETURN_IF_ERROR(PrintField(proto, field, print_as_string));
       }
@@ -347,7 +348,7 @@ class Printer {
       } else {
         int field_size = reflection->FieldSize(containing_proto, field);
 
-        PrintFieldPreamble(field->json_name());
+        PrintFieldPreamble(FhirJsonName(field));
         output_ += "[";
         Indent();
         AddNewline();
@@ -370,9 +371,9 @@ class Printer {
       if (IsPrimitive(field->message_type())) {
         FHIR_RETURN_IF_ERROR(
             PrintPrimitiveField(reflection->GetMessage(containing_proto, field),
-                                field->json_name()));
+                                FhirJsonName(field)));
       } else {
-        PrintFieldPreamble(field->json_name());
+        PrintFieldPreamble(FhirJsonName(field));
         FHIR_RETURN_IF_ERROR(
             PrintNonPrimitive(reflection->GetMessage(containing_proto, field)));
       }
@@ -432,7 +433,7 @@ class Printer {
     }
     const google::protobuf::FieldDescriptor* value_field =
         choice_reflection->GetOneofFieldDescriptor(choice_container, oneof);
-    std::string oneof_field_name = value_field->json_name();
+    std::string oneof_field_name = FhirJsonName(value_field);
     oneof_field_name[0] = toupper(oneof_field_name[0]);
 
     if (IsPrimitive(value_field->message_type())) {
@@ -474,7 +475,7 @@ class Printer {
     }
 
     if (non_null_values_found) {
-      PrintFieldPreamble(field->json_name());
+      PrintFieldPreamble(FhirJsonName(field));
       output_ += "[";
       Indent();
       for (const JsonPrimitive& json_primitive : json_primitives) {
@@ -493,7 +494,7 @@ class Printer {
         output_ += ",";
         AddNewline();
       }
-      PrintFieldPreamble(absl::StrCat("_", field->json_name()));
+      PrintFieldPreamble(absl::StrCat("_", FhirJsonName(field)));
       output_ += "[";
       Indent();
       for (const JsonPrimitive& json_primitive : json_primitives) {
diff --git a/cc/google/fhir/json_util.cc b/cc/google/fhir/json_util.cc
index 8bda7001d..069b745e3 100644
--- a/cc/google/fhir/json_util.cc
+++ b/cc/google/fhir/json_util.cc
@@ -18,10 +18,12 @@
 
 #include <string>
 
+#include "google/protobuf/descriptor.h"
 #include "absl/container/flat_hash_map.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
 #include "absl/strings/string_view.h"
+#include "google/fhir/annotations.h"
 
 namespace google::fhir {
 
@@ -60,4 +62,15 @@ absl::StatusOr<std::string> ToJsonStringValue(absl::string_view raw_value) {
   return result;
 }
 
+const std::string& FhirJsonName(const google::protobuf::FieldDescriptor* field) {
+  // When translating References between proto and JSON, the unstructured
+  // FHIR JSON Reference.reference field maps to the absolute URI field
+  // in the proto Reference.
+  static const std::string* kReferenceFieldName = new std::string("reference");
+  if (field->name() == "uri" && IsReference(field->containing_type())) {
+    return *kReferenceFieldName;
+  }
+  return field->json_name();
+}
+
 }  // namespace google::fhir
diff --git a/cc/google/fhir/json_util.h b/cc/google/fhir/json_util.h
index 4ee380e73..c84ed44d1 100644
--- a/cc/google/fhir/json_util.h
+++ b/cc/google/fhir/json_util.h
@@ -19,6 +19,7 @@
 
 #include <string>
 
+#include "google/protobuf/descriptor.h"
 #include "absl/status/statusor.h"
 #include "absl/strings/string_view.h"
 
@@ -44,6 +45,9 @@ namespace google::fhir {
 // http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf
 absl::StatusOr<std::string> ToJsonStringValue(absl::string_view raw_value);
 
+// Given a proto field, returns the name of the field in FHIR JSON.
+const std::string& FhirJsonName(const google::protobuf::FieldDescriptor* field);
+
 }  // namespace google::fhir
 
 #endif  // GOOGLE_FHIR_JSON_UTIL_H_
diff --git a/cc/google/fhir/json_util_test.cc b/cc/google/fhir/json_util_test.cc
index 9e7c86873..ff31b63d7 100644
--- a/cc/google/fhir/json_util_test.cc
+++ b/cc/google/fhir/json_util_test.cc
@@ -16,13 +16,19 @@
 
 #include "google/fhir/json_util.h"
 
-#include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "google/fhir/status/status.h"
+#include "proto/google/fhir/proto/r4/core/datatypes.pb.h"
+#include "proto/google/fhir/proto/r4/core/resources/observation.pb.h"
+#include "proto/google/fhir/proto/r4/core/resources/patient.pb.h"
 
 namespace google::fhir {
 namespace {
 
+using ::google::fhir::r4::core::Observation;
+using ::google::fhir::r4::core::Patient;
+using ::google::fhir::r4::core::Reference;
+
 void TestToJsonStringValue(std::string input, std::string expected) {
   absl::StatusOr<std::string> result = ToJsonStringValue(input);
   FHIR_ASSERT_OK(result.status());
@@ -54,5 +60,31 @@ TEST(JsonUtilTest, ToJsonStringValueInvalidControlCharactersReturnsError) {
   EXPECT_FALSE(result.ok());
 }
 
+TEST(JsonUtilTest, FhirJsonNameNonReferenceSucceeds) {
+  EXPECT_EQ(
+      FhirJsonName(Patient::GetDescriptor()->FindFieldByName("implicit_rules")),
+      "implicitRules");
+}
+
+TEST(JsonUtilTest, FhirJsonNameNonReferenceWithExplicitJsonNameSucceeds) {
+  EXPECT_EQ(FhirJsonName(Observation::Component::ValueX::GetDescriptor()
+                             ->FindFieldByName("string_value")),
+            "string");
+}
+
+TEST(JsonUtilTest, FhirJsonNameReferenceUriSucceeds) {
+  EXPECT_EQ(FhirJsonName(Reference::GetDescriptor()->FindFieldByName("uri")),
+            "reference");
+}
+
+TEST(JsonUtilTest, FhirJsonNameReferenceOtherFieldSucceeds) {
+  EXPECT_EQ(
+      FhirJsonName(Reference::GetDescriptor()->FindFieldByName("fragment")),
+      "fragment");
+  EXPECT_EQ(
+      FhirJsonName(Reference::GetDescriptor()->FindFieldByName("patient_id")),
+      "patientId");
+}
+
 }  // namespace
 }  // namespace google::fhir
diff --git a/cc/google/fhir/r4/BUILD b/cc/google/fhir/r4/BUILD
index dc6732a1b..ca033d4cb 100644
--- a/cc/google/fhir/r4/BUILD
+++ b/cc/google/fhir/r4/BUILD
@@ -178,13 +178,14 @@ cc_test(
         ":operation_error_reporter",
         ":primitive_handler",
         ":profiles",
+        ":resource_validation",
         "//cc/google/fhir:error_reporter",
         "//cc/google/fhir:proto_util",
-        "//cc/google/fhir:test_helper",
         "//cc/google/fhir/json:fhir_json",
         "//cc/google/fhir/json:json_sax_handler",
         "//cc/google/fhir/json:test_matchers",
         "//cc/google/fhir/status",
+        "//cc/google/fhir/status:statusor",
         "//cc/google/fhir/testutil:generator",
         "//cc/google/fhir/testutil:proto_matchers",
         "//proto/google/fhir/proto:annotations_cc_proto",
@@ -339,6 +340,7 @@ cc_test(
         "//proto/google/fhir/proto/r4/core/resources:verification_result_cc_proto",
         "//proto/google/fhir/proto/r4/core/resources:vision_prescription_cc_proto",
         "//testdata/r4/profiles:test_cc_proto",
+        "@com_google_absl//absl/log:check",
         "@com_google_absl//absl/status:statusor",
         "@com_google_absl//absl/strings",
         "@com_google_googletest//:gtest_main",
diff --git a/cc/google/fhir/r4/json_format_test.cc b/cc/google/fhir/r4/json_format_test.cc
index dff2d4427..f52275d52 100644
--- a/cc/google/fhir/r4/json_format_test.cc
+++ b/cc/google/fhir/r4/json_format_test.cc
@@ -16,7 +16,9 @@
 
 #include "google/fhir/r4/json_format.h"
 
+#include <fstream>
 #include <memory>
+#include <sstream>
 #include <string>
 #include <unordered_set>
 #include <utility>
@@ -26,8 +28,10 @@
 #include "google/protobuf/text_format.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
+#include "absl/log/check.h"
 #include "absl/status/statusor.h"
 #include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
 #include "absl/strings/substitute.h"
 #include "google/fhir/error_reporter.h"
 #include "google/fhir/json/fhir_json.h"
@@ -37,8 +41,9 @@
 #include "google/fhir/r4/operation_error_reporter.h"
 #include "google/fhir/r4/primitive_handler.h"
 #include "google/fhir/r4/profiles.h"
+#include "google/fhir/r4/resource_validation.h"
 #include "google/fhir/status/status.h"
-#include "google/fhir/test_helper.h"
+#include "google/fhir/status/statusor.h"
 #include "google/fhir/testutil/generator.h"
 #include "google/fhir/testutil/proto_matchers.h"
 #include "proto/google/fhir/proto/annotations.pb.h"
@@ -213,6 +218,24 @@ using ::testing::UnorderedPointwise;
 
 static const char* const kTimeZoneString = "Australia/Sydney";
 
+inline std::string ReadFile(absl::string_view filename) {
+  std::ifstream infile;
+  infile.open(
+      absl::StrCat(getenv("TEST_SRCDIR"), "/com_google_fhir/", filename));
+
+  std::ostringstream out;
+  out << infile.rdbuf();
+  return out.str();
+}
+
+template <class T>
+T ReadProto(absl::string_view filename) {
+  T result;
+  CHECK(google::protobuf::TextFormat::ParseFromString(ReadFile(filename), &result))
+      << "Failed to parse proto in file " << filename;
+  return result;
+}
+
 // json_path should be relative to fhir root
 template <typename R>
 absl::StatusOr<R> ParseJsonToProto(const std::string& json_path) {
@@ -1710,7 +1733,7 @@ TEST(JsonFormatR4Test, PrintAndParseAllResources) {
   generator_params.optional_set_ratio_per_level = 0.05;
   generator_params.max_string_length = 200;
   auto value_provider =
-      absl::make_unique<google::fhir::testutil::RandomValueProvider>(
+      std::make_unique<google::fhir::testutil::RandomValueProvider>(
           generator_params);
 
   google::fhir::testutil::FhirGenerator generator(
@@ -1929,6 +1952,116 @@ TEST(JsonFormatR4Test,
               IgnoringRepeatedFieldOrdering(EqualsProto(expected_outcome)));
 }
 
+TEST(JsonFormatR4Test, ParseRelativeReferenceSucceeds) {
+  std::string raw_json = R"json(
+  {
+  "resourceType": "Observation",
+  "subject": {
+    "reference": "Patient/example",
+    "display": "Amy Shaw"
+  }})json";
+
+  OperationOutcome outcome;
+  OperationOutcomeErrorHandler handler(&outcome);
+  Observation resource;
+  absl::Status merge_status = ::google::fhir::r4::MergeJsonFhirStringIntoProto(
+      raw_json, &resource, absl::LocalTimeZone(), true, handler);
+
+  Observation expected;
+  ASSERT_TRUE(
+      google::protobuf::TextFormat::ParseFromString(R"pb(
+                                            subject {
+                                              patient_id { value: "example" }
+                                              display { value: "Amy Shaw" }
+                                            }
+                                          )pb",
+                                          &expected));
+
+  EXPECT_THAT(resource, EqualsProto(expected));
+}
+
+TEST(JsonFormatR4Test, ParseAbsoluteReferenceSucceeds) {
+  std::string raw_json = R"json(
+  {
+  "resourceType": "Observation",
+  "subject": {
+    "reference": "www.patient.org/123",
+    "display": "Amy Shaw"
+  }})json";
+
+  OperationOutcome outcome;
+  OperationOutcomeErrorHandler handler(&outcome);
+  Observation resource;
+  absl::Status merge_status = ::google::fhir::r4::MergeJsonFhirStringIntoProto(
+      raw_json, &resource, absl::LocalTimeZone(), true, handler);
+
+  Observation expected;
+  ASSERT_TRUE(google::protobuf::TextFormat::ParseFromString(
+      R"pb(
+        subject {
+          uri { value: "www.patient.org/123" }
+          display { value: "Amy Shaw" }
+        }
+      )pb",
+      &expected));
+
+  EXPECT_THAT(resource, EqualsProto(expected));
+}
+
+TEST(JsonFormatR4Test, PrintRelativeReferenceSucceeds) {
+  Observation proto_form;
+  ASSERT_TRUE(
+      google::protobuf::TextFormat::ParseFromString(R"pb(
+                                            subject {
+                                              patient_id { value: "example" }
+                                              display { value: "Amy Shaw" }
+                                            }
+                                          )pb",
+                                          &proto_form));
+
+  OperationOutcome outcome;
+  OperationOutcomeErrorHandler handler(&outcome);
+  Observation resource;
+  FHIR_ASSERT_OK_AND_ASSIGN(
+      std::string json,
+      ::google::fhir::r4::PrettyPrintFhirToJsonString(proto_form));
+
+  EXPECT_EQ(json, R"json({
+  "resourceType": "Observation",
+  "subject": {
+    "reference": "Patient/example",
+    "display": "Amy Shaw"
+  }
+})json");
+}
+
+TEST(JsonFormatR4Test, PrintAbsoluteReferenceSucceeds) {
+  Observation proto_form;
+  ASSERT_TRUE(google::protobuf::TextFormat::ParseFromString(
+      R"pb(
+        subject {
+          uri { value: "www.patient.org/123" }
+          display { value: "Amy Shaw" }
+        }
+      )pb",
+      &proto_form));
+
+  OperationOutcome outcome;
+  OperationOutcomeErrorHandler handler(&outcome);
+  Observation resource;
+  FHIR_ASSERT_OK_AND_ASSIGN(
+      std::string json,
+      ::google::fhir::r4::PrettyPrintFhirToJsonString(proto_form));
+
+  EXPECT_EQ(json, R"json({
+  "resourceType": "Observation",
+  "subject": {
+    "reference": "www.patient.org/123",
+    "display": "Amy Shaw"
+  }
+})json");
+}
+
 }  // namespace
 
 }  // namespace r4
diff --git a/cc/google/fhir/references.cc b/cc/google/fhir/references.cc
index 13146e59b..139dbbcec 100644
--- a/cc/google/fhir/references.cc
+++ b/cc/google/fhir/references.cc
@@ -16,8 +16,21 @@
 
 #include "google/fhir/references.h"
 
+#include <memory>
+#include <string>
+
+#include "google/protobuf/descriptor.h"
+#include "google/protobuf/message.h"
+#include "absl/memory/memory.h"
+#include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/str_cat.h"
+#include "absl/types/optional.h"
+#include "google/fhir/proto_util.h"
+#include "google/fhir/status/status.h"
+#include "google/fhir/status/statusor.h"
 #include "google/fhir/util.h"
+#include "re2/re2.h"
 
 namespace google {
 namespace fhir {