APA (7th ed.) Citation

Le Queux, W. (2012). The German Spy System from Within. Project Gutenberg.

Chicago Style (17th ed.) Citation

Le Queux, William. The German Spy System from Within. Project Gutenberg, 2012.

MLA (9th ed.) Citation

Le Queux, William. The German Spy System from Within. Project Gutenberg, 2012.

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