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Longmans, Green, 1932
Buku Teks
Agus Pakpahan
BRI, 2004
Buku Teks
Sayers, R.S., author
Clarendon Press, 1958
Buku Teks
Basu, S.K.
Macmillan Press, 1974
Buku Teks
Lelyana Mayasari, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2012
UI - Tesis (Open)