Friedman, Barbara G., author
Lawrence Erlbaum Associates, 2005
Buku Teks
Hutahuruk, Toho Jefta, author
2006
Artikel Jurnal
edited by C.J. Armstrong and J.A. Large
Gower, 1988
Buku Referensi
edited by C.J. Armstrong and J.A. Large
Ashgate, 1992
Buku Referensi
Bell, Suzanne S., author
Libraries Unlimited, 2015
Buku Teks