I just sent an email to this person:
http://www.stockyard.net/cgi-bin/classifieds/classifieds.cgi?session_key=&search_and_display_db_button=on&db_id=20109&query=retrieval IMO if you don't know the difference between the two, it's prob best to get some instruction or go to some clinics FIRST before the "try this at home" technique... whaddaya reckon?