Fundación Ambio; Deutsche Gesellschaft für Technische Zusammenarbeit; Centro Panamericano de Ingeniería Sanitaria y Ciencias del Ambiente(Fundacion Ambio, San José, CR, 1993)
Cornell University, Cornell International Institute for Food, Agriculture and Development; Centro Agronómico Tropical de Investigación y Enseñanza; Thurston, H.D.; Smith, M.; Abawi, George; Kearl, S.(CIIFAD, Ithaca, NY, US, 1994)
Pakistan Council of Scientific and Industrial Research Laboratories, Applied Chemistry Research Centre; Saeed, M.A.; Badruddin, Dr.; Broadbent, A.D.(PCSIR Laboratories Complex, Lahore, PK, 1991)
Singapore Institute of Standards and Industrial Research; Saskatchewan Research Council; University of Saskatchewan(Saskatchewan Research Council, Saskatoon, SK, CA, 1992)