Overbeek, J. (1970). Comparative thoughts on overpopulation between the two world wars. Drukkerij Princo.
Lua i Stíl Chicago (17ú heag.)Overbeek, Johannes. Comparative Thoughts on Overpopulation Between the Two World Wars. Rotterdam: Drukkerij Princo, 1970.
Lua MLA (8ú heag.)Overbeek, Johannes. Comparative Thoughts on Overpopulation Between the Two World Wars. Drukkerij Princo, 1970.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.