diff --git a/src/spinneret/graph.py b/src/spinneret/graph.py
index af263f0..2fbe2d9 100644
--- a/src/spinneret/graph.py
+++ b/src/spinneret/graph.py
@@ -20,16 +20,166 @@ def create_graph(metadata_files: list = None, vocabulary_files: list = None) ->
     # Load metadata
     if metadata_files is not None:
         for filename in metadata_files:
-            g.parse(filename)
+            g.parse(filename, format="json-ld")
 
     # Load vocabularies
     if vocabulary_files is not None:
         for filename in vocabulary_files:
             g.parse(filename, format=guess_format(filename))
 
+    # Some string literals should be converted to URIRefs to create linked
+    # data with vocabularies. These are often cases where SOSO conventions
+    # recommend connecting the value to an object property (e.g. `url`) rather
+    # than the object @id. The following code makes these conversions based on
+    # where vocabulary URIs can be used in SOSO markup.
+    g = convert_keyword_url_to_uri(g)
+    g = convert_variable_property_id_to_uri(g)
+    g = convert_variable_measurement_technique_to_uri(g)
+    g = convert_variable_unit_code_to_uri(g)
+    g = convert_license_to_uri(g)
+
     return g
 
 
+def convert_keyword_url_to_uri(graph: Graph) -> Graph:
+    """
+    :param graph: Graph of metadata and vocabularies
+    :returns: Graph with keyword URLs converted to URIs
+    :notes: Converts values of `schema:keyword/schema:DefinedTerm/schema:url`
+        to URI references if the value appears to be a URL.
+    """
+    update_request = """
+    PREFIX schema: <https://schema.org/>
+
+    DELETE {
+        ?term schema:url ?value .
+    }
+    INSERT {
+        ?term schema:url ?newURI .
+    }
+    WHERE {
+        ?dataset schema:keywords ?term .
+        ?term a schema:DefinedTerm .
+        ?term schema:url ?value .
+        FILTER (isLiteral(?value) && REGEX(?value, "^https?://", "i")) .
+        BIND (URI(?value) AS ?newURI)
+    }
+    """
+    graph.update(update_request)
+    return graph
+
+
+def convert_variable_property_id_to_uri(graph: Graph) -> Graph:
+    """
+    :param graph: Graph of metadata and vocabularies
+    :returns: Graph with variable property IDs converted to URIs
+    :notes: Converts values of `schema:variableMeasured/schema:PropertyValue/
+        schema:propertyID` to URI references if the value appears to be a URL.
+    """
+    update_request = """
+    PREFIX schema: <https://schema.org/>
+
+    DELETE {
+        ?term schema:propertyID ?value .
+    }
+    INSERT {
+        ?term schema:propertyID ?newURI .
+    }
+    WHERE {
+        ?dataset schema:variableMeasured ?term .
+        ?term a schema:PropertyValue .
+        ?term schema:propertyID ?value .
+        FILTER (isLiteral(?value) && REGEX(?value, "^https?://", "i")) .
+        BIND (URI(?value) AS ?newURI)
+    }
+    """
+    graph.update(update_request)
+    return graph
+
+
+def convert_variable_measurement_technique_to_uri(graph: Graph) -> Graph:
+    """
+    :param graph: Graph of metadata and vocabularies
+    :returns: Graph with variable measurement techniques converted to URIs
+    :notes: Converts values of `schema:variableMeasured/schema:PropertyValue/
+        schema:measurementTechnique` to URI references if the value appears to
+        be a URL.
+    """
+    update_request = """
+    PREFIX schema: <https://schema.org/>
+
+    DELETE {
+        ?term schema:measurementTechnique ?value .
+    }
+    INSERT {
+        ?term schema:measurementTechnique ?newURI .
+    }
+    WHERE {
+        ?dataset schema:variableMeasured ?term .
+        ?term a schema:PropertyValue .
+        ?term schema:measurementTechnique ?value .
+        FILTER (isLiteral(?value) && REGEX(?value, "^https?://", "i")) .
+        BIND (URI(?value) AS ?newURI)
+    }
+    """
+    graph.update(update_request)
+    return graph
+
+
+def convert_variable_unit_code_to_uri(graph: Graph) -> Graph:
+    """
+    :param graph: Graph of metadata and vocabularies
+    :returns: Graph with variable unit codes converted to URIs
+    :notes: Converts values of `schema:variableMeasured/schema:PropertyValue/
+        schema:unitCode` to URI references if the value appears to be a URL.
+    """
+    update_request = """
+    PREFIX schema: <https://schema.org/>
+
+    DELETE {
+        ?term schema:unitCode ?value .
+    }
+    INSERT {
+        ?term schema:unitCode ?newURI .
+    }
+    WHERE {
+        ?dataset schema:variableMeasured ?term .
+        ?term a schema:PropertyValue .
+        ?term schema:unitCode ?value .
+        FILTER (isLiteral(?value) && REGEX(?value, "^https?://", "i")) .
+        BIND (URI(?value) AS ?newURI)
+    }
+    """
+    graph.update(update_request)
+    return graph
+
+
+def convert_license_to_uri(graph: Graph) -> Graph:
+    """
+    :param graph: Graph of metadata and vocabularies
+    :returns: Graph with licenses converted to URIs
+    :notes: Converts values of `schema:license` to URI references if the value
+        appears to be a URL.
+    """
+    update_request = """
+    PREFIX schema: <https://schema.org/>
+
+    DELETE {
+        ?dataset schema:license ?value .
+    }
+    INSERT {
+        ?dataset schema:license ?newURI .
+    }
+    WHERE {
+        ?dataset schema:license ?value .
+        FILTER (isLiteral(?value) && REGEX(?value, "^https?://", "i")) .
+        BIND (URI(?value) AS ?newURI)
+    }
+    """
+    graph.update(update_request)
+    return graph
+
+
 if __name__ == "__main__":
     # Example usage
     WORKING_DIR = "/Users/csmith/Data/soso/all_edi_test_results"
diff --git a/tests/test_graph.py b/tests/test_graph.py
index ee1a67d..a8cf0cf 100644
--- a/tests/test_graph.py
+++ b/tests/test_graph.py
@@ -2,7 +2,15 @@
 
 from os import listdir
 import importlib
-from spinneret.graph import create_graph
+from rdflib import Graph, Literal, URIRef
+from spinneret.graph import (
+    create_graph,
+    convert_keyword_url_to_uri,
+    convert_variable_property_id_to_uri,
+    convert_variable_measurement_technique_to_uri,
+    convert_variable_unit_code_to_uri,
+    convert_license_to_uri,
+)
 
 
 def test_create_graph():
@@ -26,3 +34,335 @@ def test_create_graph():
     res = create_graph(metadata_files=metadata_files, vocabulary_files=vocabulary_files)
     assert res is not None
     assert len(res) == 668  # based on current metadata and vocabulary files
+
+
+def test_convert_keyword_url_to_uri_converts_if_url():
+    """Test that the convert_keyword_url_to_uri function applies the conversion
+    if the value looks like a URL"""
+
+    test_data = """
+    {
+        "@context": {"@vocab": "https://schema.org/"},
+        "@type": "Dataset",
+        "keywords": [
+            {
+                "@type": "DefinedTerm",
+                "url": "http://purl.obolibrary.org/obo/CHEBI_33284"
+            }
+        ]
+    }
+    """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_keyword_url_to_uri(g)
+    query = """
+        PREFIX schema: <https://schema.org/>
+
+        SELECT ?url
+        WHERE {
+          ?dataset schema:keywords ?term .
+          ?term a schema:DefinedTerm .
+          ?term schema:url ?url .
+        }
+        """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], URIRef)  # is now a URIRef
+
+
+def test_convert_keyword_url_to_uri_does_not_convert_if_text():
+    """Test that the convert_keyword_url_to_uri function does not apply the
+    conversion if the value does not look like a URL"""
+
+    test_data = """
+    {
+        "@context": {"@vocab": "https://schema.org/"},
+        "@type": "Dataset",
+        "keywords": [
+            {
+                "@type": "DefinedTerm",
+                "url": "not URL formatted text"
+            }
+        ]
+    }
+    """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_keyword_url_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?url
+    WHERE {
+      ?dataset schema:keywords ?term .
+      ?term a schema:DefinedTerm .
+      ?term schema:url ?url .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], Literal)  # is still a Literal
+
+
+def test_convert_variable_property_id_to_uri_converts_if_url():
+    """Test that the convert_variable_property_id_to_uri function applies the
+    conversion if the value looks like a URL"""
+
+    test_data = """
+    {
+        "@context": {"@vocab": "https://schema.org/"},
+        "@type": "Dataset",
+        "variableMeasured": [
+            {
+                "@type": "PropertyValue",
+                "propertyID": "http://purl.dataone.org/odo/ECSO_00002566"
+            }
+        ]
+    }
+    """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_variable_property_id_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?propertyID
+    WHERE {
+      ?dataset schema:variableMeasured ?term .
+      ?term a schema:PropertyValue .
+      ?term schema:propertyID ?propertyID .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], URIRef)  # is now a URIRef
+
+
+def test_convert_variable_property_id_to_uri_does_not_convert_if_text():
+    """Test that the convert_variable_property_id_to_uri function does not
+    apply the conversion if the value does not look like a URL"""
+
+    test_data = """
+    {
+        "@context": {"@vocab": "https://schema.org/"},
+        "@type": "Dataset",
+        "variableMeasured": [
+            {
+                "@type": "PropertyValue",
+                "propertyID": "not URL formatted text"
+            }
+        ]
+    }
+    """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_variable_property_id_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?propertyID
+    WHERE {
+      ?dataset schema:variableMeasured ?term .
+      ?term a schema:PropertyValue .
+      ?term schema:propertyID ?propertyID .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], Literal)  # is now a URIRef
+
+
+def test_convert_variable_measurement_technique_to_uri_converts_if_url():
+    """Test that the convert_variable_measurement_technique_to_uri function
+    applies the conversion if the value looks like a URL"""
+
+    test_data = """
+    {
+        "@context": {"@vocab": "https://schema.org/"},
+        "@type": "Dataset",
+        "variableMeasured": [
+            {
+                "@type": "PropertyValue",
+                "measurementTechnique": "http://example.org/method/8675309"
+            }
+        ]
+    }
+    """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_variable_measurement_technique_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?value
+    WHERE {
+      ?dataset schema:variableMeasured ?term .
+      ?term a schema:PropertyValue .
+      ?term schema:measurementTechnique ?value .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], URIRef)  # is now a URIRef
+
+
+def test_convert_variable_measurement_technique_to_uri_does_not_convert_if_text():
+    """Test that the convert_variable_measurement_technique_to_uri function
+    does not apply the conversion if the value does not look like a URL"""
+
+    test_data = """
+    {
+        "@context": {"@vocab": "https://schema.org/"},
+        "@type": "Dataset",
+        "variableMeasured": [
+            {
+                "@type": "PropertyValue",
+                "measurementTechnique": "not URL formatted text"
+            }
+        ]
+    }
+    """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_variable_measurement_technique_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?value
+    WHERE {
+      ?dataset schema:variableMeasured ?term .
+      ?term a schema:PropertyValue .
+      ?term schema:measurementTechnique ?value .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], Literal)  # is still a Literal
+
+
+def test_convert_variable_unit_code_to_uri_converts_if_url():
+    """Test that the convert_variable_unit_code_to_uri function applies the
+    conversion if the value looks like a URL"""
+    test_data = """
+    {
+        "@context": {"@vocab": "https://schema.org/"},
+        "@type": "Dataset",
+        "variableMeasured": [
+            {
+                "@type": "PropertyValue",
+                "unitCode": "http://example.org/unit/2112"
+            }
+        ]
+    }
+    """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_variable_unit_code_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?value
+    WHERE {
+      ?dataset schema:variableMeasured ?term .
+      ?term a schema:PropertyValue .
+      ?term schema:unitCode ?value .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], URIRef)  # is now a URIRef
+
+
+def test_convert_variable_unit_code_to_uri_does_not_convert_if_text():
+    """Test that the convert_variable_unit_code_to_uri function does not apply
+    the conversion if the value does not look like a URL"""
+    test_data = """
+    {
+        "@context": {"@vocab": "https://schema.org/"},
+        "@type": "Dataset",
+        "variableMeasured": [
+            {
+                "@type": "PropertyValue",
+                "unitCode": "not URL formatted text"
+            }
+        ]
+    }
+    """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_variable_unit_code_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?value
+    WHERE {
+      ?dataset schema:variableMeasured ?term .
+      ?term a schema:PropertyValue .
+      ?term schema:unitCode ?value .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], Literal)  # is still a Literal
+
+
+def test_convert_license_to_uri_converts_if_url():
+    """Test that the convert_license_to_uri function applies the conversion if
+    the value looks like a URL"""
+    test_data = """
+        {
+            "@context": {"@vocab": "https://schema.org/"},
+            "@type": "Dataset",
+            "license": "http://spdx.org/licenses/CC0-1.0"
+        }
+        """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_license_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?value
+    WHERE {
+      ?dataset schema:license ?value .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], URIRef)  # is now a URIRef
+
+
+def test_convert_license_to_uri_does_not_convert_if_text():
+    """Test that the convert_license_to_uri function does not apply the
+    conversion if the value does not look like a URL"""
+    test_data = """
+        {
+            "@context": {"@vocab": "https://schema.org/"},
+            "@type": "Dataset",
+            "license": "not URL formatted text"
+        }
+        """
+    g = Graph()
+    g.parse(data=test_data, format="json-ld")
+
+    g = convert_license_to_uri(g)
+    query = """
+    PREFIX schema: <https://schema.org/>
+
+    SELECT ?value
+    WHERE {
+      ?dataset schema:license ?value .
+    }
+    """
+    results = g.query(query)
+    for result in results:
+        assert isinstance(result[0], Literal)  # is still a Literal