Beamer, Linda
[Publisher not identified], [Date of publication not identified]
Buku Teks
Tubbs, Stewart L.
McGraw-Hill, 2008
Buku Teks SO
edited Martin Lea
Harvester Wheatscheaf, 1992
Buku Teks SO
Varner, Iris V.
Richard D. Irwin, 1995
Buku Teks SO
Scollon, Ronald
Blackwell Publishing, 2001
Buku Teks SO