Title: Castle (DK Eyewitness Books Series), Author: Christopher Gravett
Title: GREAT WALL OF CHINA, THE, Author: Leonard Everett Fisher
Title: Besieged: An Encyclopedia of Great Sieges from Ancient Times to the Present, Author: Paul K. Davis
Title: Modern European Military Fortifications, 1870-1950: A Selective Annotated Bibliography, Author: J.E Kaufmann