Jitender Kumar , Y. P. Singh and D. K. Rana. “Yield and Gap Analysis of Wheat (Triticum Aestivum) Productivity in NCR of Delhi”. Indian Journal of Extension Education, vol. 50, no. 1&2, June 2014, pp. 56-58, https://epubs.icar.org.in/index.php/IJEE/article/view/144307.