1. International Potato Center (CIP); P.O. Box 1558 Lima 12 Perú
2. Universidad Mayor de San Marcos, FCF-DAFI; P.O. Box 10584 Lima 1 Perú
3. Dep. of Environmental Sciences; Rutgers Univ.; 14 College Farm Road New Brunswick NJ 08901
4. Dep. of Land Resource Science; Univ. of Guelph; Guelph ON Canada