APA (7th ed.) Citation

Skillen, H. (1992). Enigma and its Achilles heel. Privately printed.

Chicago Style (17th ed.) Citation

Skillen, Hugh. Enigma and Its Achilles Heel. Pinner: Privately printed, 1992.

MLA (8th ed.) Citation

Skillen, Hugh. Enigma and Its Achilles Heel. Privately printed, 1992.

Warning: These citations may not always be 100% accurate.