Walker EA, Picker MJ, Granger AL, Dykstra LA. Effects of opioids in morphine-treated pigeons trained to discriminate among morphine, the low-efficacy agonist nalbuphine, and saline. J Pharmacol Exp Ther. 2004 Jul;310(1):150-8.
Williams VS, Smith MY, Fehnel SE. Use of bpi interference measures for assessing change in impact of pain. Poster presented at the 23rd Annual Scientific Meeting of the American Pain Society; May 2004.
Gan TJ, Lubarsky DA, Flood EM, Thanh T, Mauskopf J, Mayne T, Chen C. Patient preferences for acute pain treatment. Br J Anaesth. 2004 May 1;92(5):681-8.