Good Ranger source. Written by a PhD historian, three strikes you're out, Hey? This PhD is an Airborne Ranger. Official Command and Staff, Ft. Leavenworth document.
http://www-cgsc.army.mil/carl/resources/csi/King/King.asp
Fantastic reading list.
http://www-cgsc.army.mil/carl/resources/csi/berlin/berlin.asp#General%20Studies