MLA

Gummere, Richard M, and Lucius Annaeus Seneca. Epistles. Cambridge, Mass: Harvard University Press, 1996.

APA

Gummere, R. M, & Seneca, L. Annaeus. (1996). Epistles. Cambridge, Mass: Harvard University Press.

Chicago

Seneca, Lucius Annaeus Epistles. Translated by Richard M Gummere. Cambridge, Mass: Harvard University Press, 1996.