APA (7th ed.) Citation

Yeats, W. B. (2003). The Celtic Twilight. Project Gutenberg.

Chicago Style (17th ed.) Citation

Yeats, W. B. The Celtic Twilight. Project Gutenberg, 2003.

MLA (9th ed.) Citation

Yeats, W. B. The Celtic Twilight. Project Gutenberg, 2003.

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