Synonyms: 5,6,7,8-Ethanediylidene-1H-cyclobuta(d)(1,2,4)triazolo(1,2-a)pyridazine-6(7H)-carbonitrile, hexahydro-1,3-dioxo-2-phenyl-;5,6,7,8-Ethanediylidene-1H-cyclobuta[d][1,2,4]triazolo[1,2-a]pyridazine-6(7H)-carbonitrile, hexahydro-1,3-dioxo-2-phenyl-