Campbell, R. N., & Lindfors, J. W. (1969). Insights into English structure: A programmed course. Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)Campbell, Russell N., agus Judith W. Lindfors. Insights into English Structure: A Programmed Course. Englewood Cliffs, N. J: Prentice-Hall, 1969.
Lua MLA (9ú heag.)Campbell, Russell N., agus Judith W. Lindfors. Insights into English Structure: A Programmed Course. Prentice-Hall, 1969.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.