Navarrete-Vazquez, Gabriel; Moreno-Diaz, Hermenegilda; Estrada-Soto, Samuel; Torres-Piedra, Mariana; Leon-Rivera, Ismael; Tlahuext, Hugo; Munoz-Muniz, Omar; Torres-Gomez, Hector Synthetic Communications, 2007 , vol. 37, # 17 p. 2815 - 2825