Said, Zainuddin; Tillett, John G.
Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999), 1982 , p. 701 - 706

Shevelev; Dalinger; Gulevskaya; Cherkasova; Vinogradov; Ugrak; Starosotnikov
Chemistry of Heterocyclic Compounds, 1999 , vol. 35, # 3 p. 363 - 373