Jensen,K.A. et al.
Acta Chemica Scandinavica (1947-1973), 1968 , vol. 22, p. 1 - 50

Singh, Shailendra; Husain, Kakul; Athar, Fareeda; Azam, Amir
European Journal of Pharmaceutical Sciences, 2005 , vol. 25, # 2-3 p. 255 - 262