1,3,4-Thiadiazolo(3',2':1,2)pyrimido(5,4-b)indol-5(6H)-one, 2-(ethylthio)- 116989-23-2 2-(Ethylthio)-1,3,4-thiadiazolo(3',2':1,2)pyrimido(5,4-b)indol-5(6H)-one