71771-37-4;2a,4a,6a-Triaza-6b-phosphacyclopenta(cd)pentalene, hexahydro-, 6b-oxide;1,4,7-Triaza-10-phosphahexahydrotriquinacene-P-oxide;2a,4a,6a-Triaza-6b-phosphacyclopenta[cd]pentalene, hexahydro-, 6b-oxide