APA (7th ed.) Citation

Henderson, W. J. (2006). Some Forerunners of Italian Opera. Project Gutenberg.

Chicago Style (17th ed.) Citation

Henderson, W. J. Some Forerunners of Italian Opera. Project Gutenberg, 2006.

MLA (9th ed.) Citation

Henderson, W. J. Some Forerunners of Italian Opera. Project Gutenberg, 2006.

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