Ross, Peter K., author
Emerald, 2017
eBooks
Johnson, Dave, author
McGraw-Hill, 2003
Buku Teks
The Reader's Digest Association, 1988
Buku Referensi
Kim, Jae-on, author
Sage, 1978
Buku Teks
Ross, Catherine Sheldrick, author
Library Association Publishing, 1998
Buku Teks