APA (7th ed.) Citation

Vickers, K. (2012). Humphrey Duke of Gloucester A Biography. Project Gutenberg.

Chicago Style (17th ed.) Citation

Vickers, K.H. Humphrey Duke of Gloucester A Biography. Project Gutenberg, 2012.

MLA (9th ed.) Citation

Vickers, K.H. Humphrey Duke of Gloucester A Biography. Project Gutenberg, 2012.

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