Douglas, L. V. (1965). Teaching business subjects. Prentice-Hall, Inc.
Lua i Stíl Chicago (17ú heag.)Douglas, Lloyd V. Teaching Business Subjects. Prentice-Hall, Inc, 1965.
Lua MLA (8ú heag.)Douglas, Lloyd V. Teaching Business Subjects. Prentice-Hall, Inc, 1965.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.