Candrilli SD, Davis KL, Iyer S. Impact of constipation on opioid use patterns, health care resource utilization, and costs in cancer patients on opioid therapy. J Pain Palliat Care Pharmacother. 2009 Sep 1;23(3):231-41.
Morant SV, Gnanasakthy A. A new approach to the mathematical formulation of lactation curves. Anim Prod Sci. 1989 Oct;49(2):151-62.