Wellens, S. J. Houghton Mifflin English grammar and composition. Houghton Mifflin Company.
Chicago-viite (17. p.)Wellens, Sandra J. Houghton Mifflin English Grammar and Composition. Houghton Mifflin Company.
MLA-viite (8. p.)Wellens, Sandra J. Houghton Mifflin English Grammar and Composition. Houghton Mifflin Company.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.