Klein; Berkowitz
Journal of the American Chemical Society, 1959 , vol. 81, p. 5160,5163

Grigor'eva, L. N.; Tikhonov, A. Ya.; Amitina, S. A.; Volodarskii, L. B.; Korobeinicheva, I. K.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1986 , vol. 22, # 3 p. 268 - 275
Khimiya Geterotsiklicheskikh Soedinenii, 1986 , vol. 22, # 3 p. 331 - 338