@BOOK {CARTER:1989a, title = {Collaborative Study of Cassava in Africa (COSCA); site selection procedure: COSCA working paper, No. 2}, author = {Carter, S. and Jones, P. }, series = {COSCA working paper}, year = {1989}, number = {2}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, note = {RTB; Root and Tuber; Cassava}, }