Hague, Paul, author
Kogen Page, 1994
Buku Referensi
edited by Di Lewis
Queensland University of Technology, 1999
Buku Teks
Bogg, Daisy, author
McGraw-Hill, 2012
Buku Teks
Sklare, Arnold B., author
McGraw-Hill, 1964
Buku Teks
Waldo, Willis H., author
Van Nostrand Reinhold, 1960
Koleksi Publik