Avif Hidayaturohman
Seskoal Press, 2020
Artikel Jurnal
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Westview Press, 1978
Buku Teks
Dinerstein, H.S.
Frederick A. Praeger, 1962
Buku Teks
Windrow, Martin
Grange Books, 2000
Buku Referensi
Dahl, Robert A., 1915-2014
Prentice-Hall, 1978
Buku Teks SO