Hamburger Hill
1988 by Samuel Zaffiri
Gives a good description of the fight for Hill 937 in which the 1/506 played a large role although the main battle was fought by the 3/187th Infantry.
Ripcord
2000 by Keith Nolan
Excellent portrayal of the battles in and around Firebase Ripcord. Delta, 1/506th Infantry took significant casualties in this fight. Charlie company defended the firebase a month before the fighting took place.
Hell on a Hilltop
2004 by MG Ben Harrison
Describes the enemy the US forces faced in the Ripcord battle and their inability to reveal the facts of the battles, many years later.
Viet Nam, a History
1983 by Stanley Karnow
Excellent "big picture" book on Viet Nam.
Where we were in Viet Nam
2002 by Michael P. Kelley
Invaluable reference book. Lists most firebases and camps with grid coordinates and provides other interesting facts about the war.
101st Airborne Viet Nam 1969
Published by 101st Airborne
This is more or less a year book mailed to those who served in the 101st Airborne in 1969.