Chukwu, G.O. and Madu, T.U. (2010) Crop Water Requirement: 29 Years’ Reseach at NRCRI Umudike in Climate Change and Nigeria Environment. In: Anyadike, R.N.C., Madu, I.A. and Ajaero, C.K., Eds., Climate Change and Nigeria Environment, Department of Geography University of Nsukka Conference Proceedings, 185-199.
 Machelle, W. and Joel, G. (2008) Soil Management NRCS National Soil Survey, ARS National Laboratory Agriculture and Environment, NCERA-59 Scientists and Department of Natural Resources and Environmental Science, University of Ilinois.
 Saied, K.D. and Narob, M.C. (2013) The Effects of 4 Types of Tillage Operations on Soil Moisture and Morphology and Performance of 3 Varieties of Cotton. European Journal of Experimental Biology, 3, 694-698.
 Mackay, A.D. and Barber, S.A. (1985) Effect of Soil Moisture and Phosphate Level on Root Hair Growth of Corn Root. Journal of Plant and Soil, 86, 321-331.
 Odjugo, A.P. (2003) An Analysis of the Effectiveness of Traditional Techniques of on Farm Micro Climate Improvement in Mid-Western Nigeria. Unpublished Ph.D. Thesis, University of Ibadan, Ibadan.