A History of Cambodia by David P. Chandler One of the major must-read studies on Cambodia history. In English
Angkor and Cambodia in the Sixteenth Century, from Spanish and Portuguese Sources] by Bernard Philippe Groslier & Charles Ralph Boxer & Michael Smithies The first and only collection of Spanish and Portuguese written sources on Angkor, predating the Angkorian "rediscovery" by more than 300 years. In English
Tonle Sap: The Heart of Cambodia's Natural Heritage by Colin M. Poole & Eleanor Briggs A geographical, historical, ecological survey of the 'Great Lake'. In English
Zhou Dagan's "Customs of Cambodia" by Michael Smithies & Zhou Daguan Another translation of the most ancient account of the life in Angkor by the Chinese merchant and traveler Zhou Daguan In English