Todd, Maria K.
CRC Press, Taylor & Francis Group, 2011
Buku Referensi
Shugar, Gershon J.
McGraw-Hill, 1990
Buku Referensi
Lewis, Jack R.
Prentice-Hall, 1982
Buku Referensi
Lock, C. B. Muriel
Clive Bingley, 1972
Buku Referensi
Sage Publications, 2009
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