Mordin M, Anastassopoulos K, van Breda A, Vallow S, Zhang M, Gargiulo K, Hewitt D, Olson W, Sikirica V. Clinical staff resource use with intravenous patient-controlled analgesia in acute postoperative pain management: results from a multicenter, prospective, observational study. J Perianesth Nurs. 2007 Aug 1;22(4):243-55.
Phanikumar CV, Maitra B. Modeling willingness-to-pay values for rural bus attributes under different trip purposes. JTRF. 2006;45(2):31-44. doi: 10.22004/ag.econ.206787