Cita APA (7a ed.)

Darwin, C. (1939). Calendar of the Letters of Charles Robert Darwin to Asa Gray. The Historical Records Survey.

Cita Chicago Style (17a ed.)

Darwin, Charles. Calendar of the Letters of Charles Robert Darwin to Asa Gray. Boston, Mass.: The Historical Records Survey, 1939.

Cita MLA (8a ed.)

Darwin, Charles. Calendar of the Letters of Charles Robert Darwin to Asa Gray. The Historical Records Survey, 1939.