9-methyl-3-methylene-1,2,3,9-tetrahydro-4H-carbazol-4-one,9-methyl-3-methylene-2,3-dihydro-1H-carbazol-4(9H)-one,"1,2,3,9-Tetrahydro-9-methyl-3-methylene-4H-carbazol-4-one is an impurity of Ondansetron .;Impurity in commercial preparations of Ondansetron",Ondansetron Impurity