Relations Ontology OntoBiotope Source
http://purl.obolibrary.org/obo/GO_0016020 http://purl.obolibrary.org/obo/OBT_000730 LOOM
http://purl.obolibrary.org/obo/CL_0000000 http://purl.obolibrary.org/obo/OBT_000061 LOOM