Harry Benjamin was a pioneer in treating the trans community.

The largest international professional organization on trans issues, HBIGDA, bears his name.

J. Michel Bailey's statistics, use of pronouns, etc., may have been largley influenced by this mid-60's report from Benjamin's _Transsexual Phenomenon_:

http://www.symposion.com/ijt/benjamin/chap_08.htm#The%20male%20transsexual's%20life%20after%20conversion