Nelson, J. L. (1977). Population and progress: Is there a conflict? (2ª ed.). Prentice Hall.
Lua i Stíl Chicago (17ú heag.)Nelson, Jack L. Population and Progress: Is There a Conflict? 2ª ed. Prentice Hall, 1977.
Lua MLA (9ú heag.)Nelson, Jack L. Population and Progress: Is There a Conflict? 2ª ed. Prentice Hall, 1977.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.