@BOOK {DVORAK:1996,
title = {Exploratory surveys in research planning: IITA research guide, No. 28},
author = {Dvorak, K. A. and Izac, A. M. N. },
series = {IITA research guide, No. 28},
year = {1996},
month = {October},
publisher = {International Instute of Tropical Agriculture (IITA)},
address = {Ibadan, Nigeria},
note = {25p.},
}