Margaret Mazzolini and Sarah Maddison
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VCJ-47RRDP7-4&_user=209810&_coverDate=04%2F30%2F2003&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1293960060&_rerunOrigin=scholar.google&_acct=C000014439&_version=1&_urlVersion=0&_userid=209810&md5=643749dee63958b0172611eed4eabb71