Hill, G. E. (1965). Management and improvement of guidance. Appleton Century Crofts.
Lua i Stíl Chicago (17ú heag.)Hill, George E. Management and Improvement of Guidance. Appleton Century Crofts, 1965.
Lua MLA (9ú heag.)Hill, George E. Management and Improvement of Guidance. Appleton Century Crofts, 1965.
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