Arms and Armour in the Medieval Teutonic Order's State in Prussia (Studies on the History of Ancient and Medieval Art of Warfar) (Hardcover)
by Andrzej Nowakowski
ISBN: 8385874011
The only place I've found with a copy is Amazon UK and its rather expensive at 44 pounds plus shipping costs to the US.
Hardcover is just what Amazon stated it was produced in. I really don't care, as long as its the English translation (as I don't speak or read Polish).
Unfortunately, most of my book collections centers around aircraft (specifically between WWII and Vietnam, with quite a bit of really rare material) and I'm just starting to collect books on armour.