Schaschke, Norbert; Assfalg-Machleidt, Irmgard; Machleidt, Werner; Turk, Dushan; Moroder, Luis Bioorganic and Medicinal Chemistry, 1997, vol. 5, # 9 p. 1789 - 1797 doi: 10.1016/S0968-0896(97)00105-3