Tran, Tuan P.; Ellsworth, Edmund L.; Watson, Brian M.; Sanchez, Joseph P.; Showalter, H. D. Hollis; Rubin, John R.; Stier, Michael A.; Yip, Judy; Nguyen, Dai Q.; Bird, Paul; Singh, Rajeshwar Journal of Heterocyclic Chemistry, 2005 , vol. 42, # 4 p. 669 - 674