History and the Khmer Rouge
When the War Was Over by Elizabeth Becker — Becker was one of the few Western journalists to enter Khmer Rouge Cambodia. Her account of the regime and its aftermath is still one of the essential reads on the period.
First They Killed My Father by Loung Ung — a memoir of surviving the Khmer Rouge as a young girl, told with unsparing clarity. One of the most powerful accounts of what the regime actually meant for ordinary Cambodians.
Sideshow: Kissinger, Nixon and the Destruction of Cambodia by William Shawcross — the definitive account of the US bombing campaign of the early 1970s and how it contributed to the Khmer Rouge's rise. Essential historical context.
The Gate by François Bizot — a French ethnologist who was held prisoner by the Khmer Rouge in 1971 and uniquely survived; his account of that experience and of watching Phnom Penh fall is unlike anything else written about Cambodia.
Travel and Culture
River of Time by Jon Swain — Swain was one of the journalists who stayed in Phnom Penh as the Khmer Rouge entered in 1975. His memoir covers Cambodia and Vietnam with a particular feel for the region in its most turbulent years.
Swimming to Cambodia by Spalding Gray — a darkly comic monologue based on Gray's time in Thailand and Cambodia during the filming of The Killing Fields. More meditation than travel guide, but captures something true about the experience of being a foreigner in this part of the world.
The Ends of the Earth by Robert D. Kaplan — includes Cambodia in a wide-ranging survey of the world's most troubled frontier zones. The Cambodia section holds up well.
For Context
Cambodia's Curse by Joel Brinkley — a Pulitzer-winning journalist's account of Cambodia in the 2000s: the corruption, the land grabs, the foreign aid industry, and the persistent grip of Hun Sen's government. Less optimistic than the tourist brochures.