Shchipanov, V. P.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1981 , vol. 17, # 7 p. 736 - 739
Khimiya Geterotsiklicheskikh Soedinenii, 1981 , # 7 p. 987 - 990

Eastman Kodak Co.
Patent: US2759821 , 1952 ;