National Council for Science and Technology; Thitai, G.; Gakuru, O.; Ng'ang'a, S.; Nyangena, R.; Njoka, J.M.(National Council for Science and Technology, Nairobi, KE, 1998)
Université de Montréal; Universidad de Chile; Pontificia Universidad Católica de Chile; Gaudry, Marc J.I.; Jara-Diaz, Sergio R.; de Dios Ortuzar, Juan(Université de Montréal, Montréal, QC, CA, 1987)