The Forts & Fortifications of Europe 1815-1945: The Central States: Germany, Austria-Hungry and CzechoslovakiaJ. E. Kaufmann
Castle to Fortress: Medieval to Post-Modern Fortifications in the Lands of the Former Roman EmpireJ. E. Kaufmann
The Forts & Fortifications of Europe 1815- 1945: The Neutral States (The Netherlands, Belgium and Switzerland): The Netherlands, Belgium and SwitzerlandJ. E. Kaufmann
Castrum to Castle: Classical to Medieval Fortifications in the Lands of the Western Roman EmpireJ. E. Kaufmann