Helfand A E, Cooke H L, Walinsky M D, Demp P H, Snyder Phillips B
Department of Community Health and Aging, Pennsylvania College of Podiatric Medicine, Philadelphia 19107, USA.
J Am Podiatr Med Assoc. 1996 Feb;86(2):93-8. doi: 10.7547/87507315-86-2-93.