Spencer, H. (1977). John Stuart Mill: His life and works : twelve sketches. Folcroft Library Editions.
Lua i Stíl Chicago (17ú heag.)Spencer, Herbert. John Stuart Mill: His Life and Works : Twelve Sketches. Folcroft, Pa.: Folcroft Library Editions, 1977.
Lua MLA (8ú heag.)Spencer, Herbert. John Stuart Mill: His Life and Works : Twelve Sketches. Folcroft Library Editions, 1977.
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