Kinghorn, J. R., Clauset, K., & Willis, C. L. (1979). A guide to four essential themes. Charles F. Kettering Foundation.
Lua i Stíl Chicago (17ú heag.)Kinghorn, Jon Rye, Karl Clauset, agus Charles L. Willis. A Guide to Four Essential Themes. Dayton, Ohio: Charles F. Kettering Foundation, 1979.
Lua MLA (9ú heag.)Kinghorn, Jon Rye, et al. A Guide to Four Essential Themes. Charles F. Kettering Foundation, 1979.
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