@INBOOK {LAGEMANN:1975a, title = {Root crop/oil palm farming systems: a case study from Eastern Nigeria}, author = {Lagemann, J and Flinn, J. C. and Okigbo, B. and Moormann, F. R. }, year = {1975}, month = {October}, type = {IITA Papers of Staff in the Agricultural Economics Sub-Program 1973 - October 1975}, pages = {1--37}, publisher = {IITA}, }