United States military helicopters - Michael Green

The helicopter came on the scene too late to play other than a minor role in the Second World War but by the Korean conflict the Bell H-13 Sioux, OH-23 Raven and Sikorsky H-19 Chickasaw were in service.
It was in Vietnam that the US military helicopters really came into their own and the best known were the Bell UH-1 Iriquois (known as the Huey), the Boeing CH-47 Chinook and the massive CH-37 Mojave.
The USAF combat search and rescue Jolly Green Giant was indispensable.
Attack helicopters have evolved from the early Huey Cobra or Snake and the Boeing AH-64 Apache came into service in the late 80s when the Sikorsky UH-60 series became the military general purpose chopper.
All these formidable aircraft and many more are covered in detail in this superbly illustrated and comprehensive book.