Langan, J. (2005). College writing skills (6th ed.). New York: McGraw-Hill.
Chicago Style aipamenaLangan, John. College Writing Skills. 6th ed. New York: McGraw-Hill, 2005.
MLA aipamenaLangan, John. College Writing Skills. 6th ed. New York: McGraw-Hill, 2005.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.