This is still my favorite --
First go here:
http://tinyurl.com/3nxaubl
Then here:
( There are two intertwined discussions here - I admittedly hijacked the thread to interject the Mark Americans photo topic -
start with post #27 by Mark(bmarlowe) on 4/15/2009 at 4:16 PM, then scroll down a ways to post at 4/16/2009 at 11:17 AM and following down a bit)
http://tinyurl.com/4x45gkh
You can read a nice summary (start on p. 4) here:
http://sabr.org/cmsFiles/Files/Mysteryphoto5-09.pdf