SHUKLA, A. K., SINGH, V. K., DWIVEDI, B. S., SHARMA, S. K., & SINGH, Y. (2011). Nitrogen use efficiencies using leaf colour chart in rice (Oryza sativa)-wheat (Triticum aestivum) cropping system. The Indian Journal of Agricultural Sciences, 76(11). https://epubs.icar.org.in/index.php/IJAgS/article/view/3259