APA (7th ed.) Citation

James, W., & James, H. (2011). The Letters of William James, Vol. II. Project Gutenberg.

Chicago Style (17th ed.) Citation

James, William, and Henry James. The Letters of William James, Vol. II. Project Gutenberg, 2011.

MLA (9th ed.) Citation

James, William, and Henry James. The Letters of William James, Vol. II. Project Gutenberg, 2011.

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