1. Tillage practices in continuous hillside farming of root crops;Abenoja;Radix,1982
2. Soil environment and yam production in three ecozones of Nigeria;Asadu,1989
3. Progress for 1977;Asian Vegetable Research and Development Center,1977
4. Area harvests equivalency ratio for measuring efficiency in multiseason intercropping;Balasubramanian;Agron. J.,1990
5. Effects of the crop rotation system on soil physical behaviour and relations with tuber yield;Bouma,1989