Callahan, Mike, author
McGraw-Hill, 1990
Buku Teks
Giuliano Lancioni, Lidia Bettini, editor
Martinus Nijhoff Publishers, 2011
Buku Teks
Hudson, Richard
Basic Blackwell , 1984
Buku Teks
Weideman, Hugh
Thomas Y. Crowell Company, 1958
Buku Referensi
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