APA (7th ed.) Citation

Gray, A., & Gray, J. L. (1973). Letters of Asa Gray. B. Franklin.

Chicago Style (17th ed.) Citation

Gray, Asa, and Jane Loring Gray. Letters of Asa Gray. New York: B. Franklin, 1973.

MLA (8th ed.) Citation

Gray, Asa, and Jane Loring Gray. Letters of Asa Gray. B. Franklin, 1973.