APA (7th ed.) Citation

Hamer, J. (1980). The twentieth century (Resource sheets, 1. publ.). MacMillan.

Chicago Style (17th ed.) Citation

Hamer, John. The Twentieth Century. Resource sheets, 1. publ. London [u.a.]: MacMillan, 1980.

MLA (9th ed.) Citation

Hamer, John. The Twentieth Century. Resource sheets, 1. publ. MacMillan, 1980.