1. Gremlin - A Graph Traversal Language. https://github.com/tinkerpop/gremlin. Gremlin - A Graph Traversal Language. https://github.com/tinkerpop/gremlin.
2. Neo4j. https://neo4j.com/. Neo4j. https://neo4j.com/.
3. Neo4j Cypher Query Language - Developer Guides. https://neo4j.com/developer/cypher/. Neo4j Cypher Query Language - Developer Guides. https://neo4j.com/developer/cypher/.
4. PGQL 1.5 Specification. https://pgql-lang.org/spec/1.5/. PGQL 1.5 Specification. https://pgql-lang.org/spec/1.5/.
5. Resource Description Framework (RDF) Model and Syntax Specification. https://www.w3.org/TR/PR-rdf-syntax/. Resource Description Framework (RDF) Model and Syntax Specification. https://www.w3.org/TR/PR-rdf-syntax/.