APA (7th ed.) Citation

Gershwin, G., Gershwin, I., & Heyward, D. Porgy and Bess.

Chicago Style (17th ed.) Citation

Gershwin, George, Ira Gershwin, and DuBose Heyward. Porgy and Bess.

MLA (9th ed.) Citation

Gershwin, George, et al. Porgy and Bess.