A. AHMED, R. P. TIWARI, and G. K. MISHRA, “Bio-stimulatory effects of bull urine (BU), PRID and GnRH on estrus induction and ovarian activity in pubertal anestrus Sahiwal heifers”, Indian J of Anim Sci, vol. 86, no. 6, pp. 643–647, Jun. 2016, doi: 10.56093/ijans.v86i6.59158.