Schiffrin, R. S. (1970). English in action: A course for spanish speaking commercial students. Longman.
Lua i Stíl Chicago (17ú heag.)Schiffrin, R. S. English in Action: A Course for Spanish Speaking Commercial Students. Gran Bretaña: Longman, 1970.
Lua MLA (9ú heag.)Schiffrin, R. S. English in Action: A Course for Spanish Speaking Commercial Students. Longman, 1970.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.