Sood A., Sharma, P.K., Tur, N.S. and Nayyar, V.K. (2009) Micronutrient Status and Their Spatial Variability in Soils of Muktsar District of Punjab—A GIS Approach. Journal of the Indian Society of Soil Science, 57, 300-306.
 Sharma, P.K., Sood, A., Setia, R.K., Tur, N.S., Mehra, D. and Singh, H. (2008) Mapping of Macronutrients in Soils of Amritsar District (Punjab)—A GIS Approach. Journal of the Indian Society of Soil Science, 56, 34-41.
 Verma, V.K., Setia, R.K., Sharma, P.K., Charanjit, S. and Ashok, K. (2005) Pedospheric Variations in Distribution of DTPA—Extractable Micronutrients in Soils Developed on Different Physiographic Units in Central Parts of Punjab, India. International Journal of Agriculture and Biology, 7, 243-247.
 Srivastava, A.K., Singh, Shyam and Das, S.N. (2010) Nutrient Optima-Based Productivity Zonality Delineation in Citrus Orchards of Northeast India. 19th World Congress of Soil Science, Soil Solutions for a Changing World, Brisbane, 1-6 August 2010.
 Zaman, Q.U. and Schumann, A.W. (2006) Nutrient Management Zones for Citrus Based on Variation in Soil Properties and Tree Performance. Precision Agriculture, 7, 45-63.