Thorn, Eric A.
Jay Books, 1989
Buku Referensi
Akester, Patricia
Sweet & Maxwel, [Date of publication not identified]
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Akester, Patricia
Sweet & Maxwell, 2008
Buku Referensi
Thorn, Eric A.
Jay Books , 1989
Buku Teks
Frederiksen, Linda
Elsevier Ltd.,, 2016
Buku Teks