Lopez, Simon E.; Rosales, Monica E.; Canelon, Carlos E.; Valverde, Edgar A.; Narvaez, Rosa C.; Charris, Jaime E.; Giannini, Fernando A.; Enriz, Ricardo D.; Carrasco, Mirta; Zacchino, Susana Heterocyclic Communications, 2001 , vol. 7, # 5 p. 473 - 480