K.K. AGRAWAL, A.P. UPADHYAY, UPENDRA SHANKER, and V.K. GUPTA. “Thermal Requirement of Sunflower Plant Types under Three Dates of Spring Planting”. Journal of Agrometeorology, vol. 4, no. 2, Dec. 2002, pp. 165-9, doi:10.54386/jam.v4i2.462.