1. Salvati P. et al; US Patent No. 4,526,892; July 2, 1985; Assigned: Farmitalia Carlo Erba, S.p.A., Milan, Italy
2. Merck Index 1603
3. I.N. p. 173
4. Klosa, J.; US Patent 3,094,531; June 18,1963; assigned to Delmar Chemicals Ltd. (Canada)
5. Kohlstaedt E. et al.; D. B. Patent No. 1,095,285; 25 Sept. 1956; Assigned to Chemiewerk Homburg Zweigniedererlassung der Deutschen Gold- und Silber-Scheideanstalt vormals Roessler Franffurt/Main