Zain, Omar Alnoor Ali Mohammed. “Effect of Water Ballast Levels in the Rear Tires on Tractor Performance Using Disc Plough on Heavy Clay Soil”. Journal of agricultural, environmental and veterinary sciences 4, no. 2 (June 30, 2020): 108–99. Accessed December 19, 2025. https://www.ajsrp.ojsexpert.com/index.php/jaevs/article/view/2617.