http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12724937&dopt=Abstract
Biomed Sci Instrum. 2003;39:466-70.
Johnson MT, McCullough J, Nindl G, Chamberlain JK.
Terre Haute Center for Medical Education, Indiana University School of Medicine, Terre Haute, IN 47809, USA.