Citazione Stile APA (7a Edizione)

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

Citazione stile Chigago Style (17a edizione)

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

Citatione MLA (9a ed.)

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