Etman, H. A.
Indian Journal of Chemistry, Section B: Organic Chemistry Including Medicinal Chemistry, 1995 , vol. 34, # 4 p. 285 - 288

Yudin, L. G.; Rumyantsev, A. N.; Sagitullin, R. S.; Kost, A. N.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1983 , p. 57 - 59
Khimiya Geterotsiklicheskikh Soedinenii, 1983 , vol. 19, # 1 p. 63 - 65