Marvin, F. S. (1917). Progress and history (2d impression.). H. Milford, Oxford University Press.
Lua i Stíl Chicago (17ú heag.)Marvin, Francis Sydney. Progress and History. 2d impression. London ; New York: H. Milford, Oxford University Press, 1917.
Lua MLA (8ú heag.)Marvin, Francis Sydney. Progress and History. 2d impression. H. Milford, Oxford University Press, 1917.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.