Synonyms: 6H-1,6,2,5a-Ethanediylidene-2H,3H,5H,8H-cyclobuta(c)furo(3,4-d)(1,2,4)triazolo(1,2-a)pyridazine -8,10(9H)-dione, dihydro-9-methyl-;6H-1,6,2,5a-Ethanediylidene-2H,3H,5H,8H-cyclobuta[c]furo[3,4-d][1,2,4]triazolo[1,2-a]pyridazine -8,10(9H)-dione, dihydro-9-methyl-