APA (7th ed.) Citation

Gumkowski, J., Leszczyński, K., & Rothert, E. (1961). Poland under Nazi occupation. Polonia Publishing House.

Chicago Style (17th ed.) Citation

Gumkowski, Janusz, Kazimierz Leszczyński, and Edward Rothert. Poland Under Nazi Occupation. Warszawa: Polonia Publishing House, 1961.

MLA (9th ed.) Citation

Gumkowski, Janusz, et al. Poland Under Nazi Occupation. Polonia Publishing House, 1961.