Terenin, V.I.; Rumynatsev, A.N.; Nosyrev, P.V.; Yudin, L.G.; Gromov, S.P.; Bundel', Yu.G. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1988 , p. 705 - 706 Khimiya Geterotsiklicheskikh Soedinenii, 1988 , vol. 24, # 6 p. 855