Stuart, Alan
Basic ideas of scientific sampling
Charles Griffin, 1976
 Buku Teks SO
Lastrucci, Carlo L.
The scientific approach: basic principles of the scientific method
Schenkman, 1964
 Buku Teks SO
Low, Ona
Proficiency in english course
Edward Arnold, 1986
 Buku Teks SO
Christhophersen, Paul
An english phonetics course
Longmans, Green, 1956
 Buku Teks SO
Swan, Michael
The Cambridge English course
Cambridge University Press, 1987
 Buku Teks