APA (7th ed.) Zitazioa
LONGMAN GROUP. (1977). LONGMAN GUIDE TO GRADED READING.
Chicago Style (17th ed.) Zitazioa
LONGMAN GROUP. LONGMAN GUIDE TO GRADED READING. 1977.
MLA (9th ed.) Zitazioa
LONGMAN GROUP. LONGMAN GUIDE TO GRADED READING. 1977.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.