Sorauf
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Burns, James McGregor, author
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Gingrich, Newt, author
Regnery, 2011
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Ausaf Ali Atiyyah, author
Fakultas Ilmu Pengetahuan Budaya Universitas Indonesia, 2017
UI - Skripsi (Membership)
Hess, Hartmut, author
International Friedrich-Erbert-Stftung (FES), 2006
Buku Teks