I've got a few, these were recommended by a few forum members who I contacted:
Cheap and Cheerful; Armies of the German Peasants' War 1524-26 (Osprey, Men at Arms), Landsknecht Woodcuts: Kriegsvolker im Zeitalter der Landsknechte, Graf August Johann Breunner, The Complete Woodcuts of Albrecht Dürer by Albrecht Durer
There are plenty out there.
Darrell.