Colonge et al.
Bulletin de la Societe Chimique de France, 1957 , p. 447

Kharchenko, V. G.; Kriven'ko, A. P.; Fedotova, O. V.; Nikolaeva, T. G.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1982 , vol. 18, # 7 p. 720 - 723
Khimiya Geterotsiklicheskikh Soedinenii, 1982 , # 7 p. 944 - 947