Fries, C. (1945). Teaching and learning english as a foreing languaje. University of Michigan.
Chicago-viite (17. p.)Fries, Charles. Teaching and Learning English as a Foreing Languaje. Ann Arbor: University of Michigan, 1945.
MLA-viite (9. p.)Fries, Charles. Teaching and Learning English as a Foreing Languaje. University of Michigan, 1945.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.