Tilley. Jefferson W.; Levitan, Paul; Kierstead, Richard W.; Cohen, Michael
Journal of Medicinal Chemistry, 1980 , vol. 23, # 12 p. 1387 - 1392

Merchan, F.; Garin, J.; Martinez, V.; Melendez, E.
Synthesis, 1982 , # 6 p. 482 - 484