Williamson, E. G., Cowan, J. L., Crawford, R. G., & Willems, V. (1966). The American student's freedom of expression: A research appraisal. University of Minnesota Press.
Lua i Stíl Chicago (17ú heag.)Williamson, E. G., John L. Cowan, R. George Crawford, agus Virginia Willems. The American Student's Freedom of Expression: A Research Appraisal. Minneapolis: University of Minnesota Press, 1966.
Lua MLA (9ú heag.)Williamson, E. G., et al. The American Student's Freedom of Expression: A Research Appraisal. University of Minnesota Press, 1966.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.