I just acquired what I believe is to be an authentic inscription and autograph of the late John F. Kennedy.   This piece came from the estate of former Michigan governor, Mennen J. Williams.  

In August 2013 this item will be sold at public auction.  However, beforehand, I would like to obtain autograph certification from a 3rd party to instill greater confidence to the future buyer of this item.

My first thought was to contact Steven Raab but after looking through his website, it does not appear that his company provides certification.   Who is the recognized authority on JFK authenticaiton?

Thanks in advance.