Walford, A. J. (1980). Walford's guide to reference material (4th ed.). The Library Association.
Lua i Stíl Chicago (17ú heag.)Walford, A. J. Walford's Guide to Reference Material. 4th ed. London: The Library Association, 1980.
Lua MLA (9ú heag.)Walford, A. J. Walford's Guide to Reference Material. 4th ed. The Library Association, 1980.
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