Vertebrate Taxonomy Ontology	National Drug Data File	Source
http://purl.bioontology.org/ontology/NDDF/002430	http://purl.obolibrary.org/obo/VTO_9026738	LOOM
http://purl.bioontology.org/ontology/NDDF/007346	http://purl.obolibrary.org/obo/VTO_0044779	LOOM
http://purl.bioontology.org/ontology/NDDF/011031	http://purl.obolibrary.org/obo/VTO_9021423	LOOM