Devils Guard - George Robert Elford, is available as a reprint (even if it is not all true, it is still a ripping yarn).
Low level Hell - Hugh L Mills. Scout pilot in vietnam. Almost rivals Chickenhawk for best 'egg beater' book out of that era.
Snake Pilot - Randy R Zahn. Cobra missions.
Dear Mom , a Snipers tale - Joseph T Ward.
Naked in DaNang - Mike Jackson. FAC pilot flying down amongst the insects in a Cessna O-2. Trying to draw fire before unleashing payloads from Phantoms onto the target. Brilliant book.
When Thunder Rolled - Ed Rasimus. Thud pilot in the early stages of the war, on Op Rolling Thunder.
Palace Cobra - Ed Rasimus. On his second tour flying Phantoms, during the Op Linebacker I & II period.