Gurstelle, W. (2014). Defending your castle: Build catapults, crossbows, moats, bulletproof shields, and more defensive devices. Chicago Review Press, Incorporated.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रGurstelle, William. Defending Your Castle: Build Catapults, Crossbows, Moats, Bulletproof Shields, and More Defensive Devices. Chicago, Illinois: Chicago Review Press, Incorporated, 2014.
एमएलए (8वां संस्करण) प्रशस्ति पत्रGurstelle, William. Defending Your Castle: Build Catapults, Crossbows, Moats, Bulletproof Shields, and More Defensive Devices. Chicago Review Press, Incorporated, 2014.
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