West, W. M. (1927). The story of world progress. Allyn and Bacon.
Lua i Stíl Chicago (17ú heag.)West, Willis M. The Story of World Progress. Boston ; New York [etc.]: Allyn and Bacon, 1927.
Lua MLA (8ú heag.)West, Willis M. The Story of World Progress. Allyn and Bacon, 1927.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.