E. R. Squibb and Sons, Inc.
Patent: US4211786 A1, 1980 ;

Khachatryan; Khachikyan; Karamyan; Panosyan; Indzhikyan
Chemistry of Heterocyclic Compounds, 2004 , vol. 40, # 4 p. 446 - 451

Bougault
Annales de Chimie (Cachan, France), 1908 , vol. <8> 15, p. 501
Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences, 1908 , vol. 146, p. 141 Anm.