Gaya APA
RICHARDS, O. (1980).
PRINCIPLES OF LANGUAGE LEARNING AND TEACHING .
GYEONGGI-DO:
HARPER PERENNIAL MODERN CLASSICS.
Gaya MLA
RICHARDS, OLLY.
"PRINCIPLES OF LANGUAGE LEARNING AND TEACHING".
GYEONGGI-DO:
HARPER PERENNIAL MODERN CLASSICS,
1980.
Text.