Prommer Eric E, Twycross Robert, Mihalyo Mary, Wilcock Andrew
Mayo Clinic Arizona, Scottsdale, Arizona, USA.
Oxford University, Oxford, United Kingdom.
J Pain Symptom Manage. 2011 Jan;41(1):140-5. doi: 10.1016/j.jpainsymman.2010.10.001. Epub 2010 Oct 20.