Cita APA (7th ed.)

Armstrong, W. H. (1967). Study is hard work (2nd ed.). Harper $ row.

Cita Chicago (17th ed.)

Armstrong, William H. Study Is Hard Work. 2nd ed. New York: Harper $ row, 1967.

Cita MLA (9th ed.)

Armstrong, William H. Study Is Hard Work. 2nd ed. Harper $ row, 1967.