A lot of good books already mentioned. Here's a few more:
Battleship Bismarck: A survivor's story - Mullenheim-Rechburg
Hitler's U-Boat War - Blair
The Two Ocean War - SE Morrison
U-Boat Commander - Prien
I-Boat Captain - Z Orita, IJN/JD Harrington
Japanese Destroyer Captain - Hara IJN
Take Her Deep! - IJ Galantin
The Other Side of the Hill- BH Liddell Hart
The Memoirs of Field Marshal Kesselring
Panzer Battles -FW Mellenthin
Tigers in the Mud -Otto Carius
Brazen Chariots -R Crisp
Flame Thrower - A Wilson
Soldat -F Knapp
Rocket Pilot - Mano Ziegler
Stuka Pilot - Rudel
The Blond Knight of Germany - Tolliver
Luftwaffe War Diaries - Cajus Bekker
Samurai! - Sakai/Caiden/Saito
To War in a Stringbag - C Lamb
The Other Battle - Hinchcliffe (Nightfighters vs Bomber Command)
Overlord - Hughes (Misleading Title. Concerns Pete Quesada and the 9th AF)
That's enough for a little while
JL