APA

Kaufmann J. E., Kaufmann H. W. & Jurga R. M. (2004). The medieval fortress: castles, forts and walled cities of the Middle Ages. Cambridge, MA: Da Capo Press.

Chicago

Kaufmann J E, Kaufmann H W and Jurga Robert M. 2004. The medieval fortress: castles, forts and walled cities of the Middle Ages. Cambridge, MA: Da Capo Press.

Harvard

Kaufmann J. E., Kaufmann H. W. and Jurga R. M. (2004). The medieval fortress: castles, forts and walled cities of the Middle Ages. Cambridge, MA: Da Capo Press.

MLA

Kaufmann J E, Kaufmann H W and Jurga Robert M. The medieval fortress: castles, forts and walled cities of the Middle Ages. Cambridge, MA: Da Capo Press. 2004.