When We Left Earth (04): Stages to Saturn

Roger E. Bilstein; Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles (University Press of Florida; 2003; ISBN 0-8130-2691-1; cover from a NASA photograph).

This one is a reprint of one of several NASA official histories that were produced (and are highly sought after). The book covers the various Saturn launch vehicles and is a absolute goldmine for the general space enthusiast/historian or even for those building models or doing artwork of the vehicles. However, due to the somewhat specialized subject, it barely missed being classified as a "essential", as I was trying to keep things from being too specialized.