APA (7th ed.) Citation

Caruso, E., & Tetrazzini, L. (2006). Caruso and Tetrazzini on the Art of Singing. Project Gutenberg.

Chicago Style (17th ed.) Citation

Caruso, Enrico, and Luisa Tetrazzini. Caruso and Tetrazzini on the Art of Singing. Project Gutenberg, 2006.

MLA (9th ed.) Citation

Caruso, Enrico, and Luisa Tetrazzini. Caruso and Tetrazzini on the Art of Singing. Project Gutenberg, 2006.

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