3-METHYL-9-BENZYLIDENE-2-AZAFLUORENE AND ITS ANALOGS СтатьяProstakov N.S., Moiz S.S., Soldatenkov A.T., Zvolinskii V.P., Cherenkova G.I.Chemistry of Heterocyclic Compounds. Том 7. 1974. С. 1305-1309