Sat Pal Saini*, Shreyansh Mittal and. “Evaluation of Nutrient Index Using Manganese As a Measure of Fertility Status of Soils under Different Cropping Systems of Punjab in North-Western India”. Journal of the Indian Society of Soil Science, vol. 68, no. 4, Feb. 2021, https://epubs.icar.org.in/index.php/JISSS/article/view/110853.