Cita APA (7th ed.)

Sheldon, L. W. (1920). Twentieth century letter writer (1a. ed.). David Mc Kay, Publisher.

Cita Chicago (17th ed.)

Sheldon, L. W. Twentieth Century Letter Writer. 1a. ed. Filadelfia: David Mc Kay, Publisher, 1920.

Cita MLA (9th ed.)

Sheldon, L. W. Twentieth Century Letter Writer. 1a. ed. David Mc Kay, Publisher, 1920.