Hudson, Kenneth
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Buku Teks
Katz, Meighen
Routledge, 2020
Buku Teks
Malof, David
Chatto & Windus, 1990
Buku Teks
editor in chief, Mortimer J. Adler
Encyclopedia Britanica, 1990
Buku Referensi
Preston, Antony
Chancellor Press , 1999
Buku Referensi