McKenna S, Doward LC. Measuring quality of life in ankylosing spondylitis. Best Pract Res Clin Rheumatol. 2008 Jan 1;6(2):12-4.
Finkelstein EA, Kosa KM. Use of incentives to motivate healthy behaviors among employees. Gender issues. 2003 Jun;21(3):50-9. doi: 10.1007/s12147-003-0005-0