1. Sandford, William P. 1938.English Theories of Public Address, 1530–1828110–111. Columbus, Ohio
2. Thonssen, Lester and Baird, A. Craig. 1948.Speech Criticism131139New York
3. Crawford, John. 1947.The Rhetoric of George Campbell, 53Northwestern University. Unpublished Ph. D. Thesis
4. Ehninger, Douglas W. 1949. “Selected Theories of Inventio in English Rhetoric, 1759–1828”. 32ff.384–391. Ohio State University. Unpublished Ph. D. Thesis
5. Series in Language and Literature, No. 1;Harrington Elbert W.,1948