Edwards, Allen L.
Holt, Rinehart and Winston, 1964
Buku Teks
Abbas Tashakkori, Charles Teddlie
SAGE Publications, 2010
Buku Teks
Runyon, Richard P.
Addison Wesley Publ., 1967
Buku Teks
Pittenger, David J., author
2003
Multimedia
Pittenger, David J., author
2003
Multimedia