Yorkey, R. C., Barrutia, R., & Uhl Chamot, A. English for International communication. Teacher´s edition.
Citazione stile Chigago Style (17a edizione)Yorkey, Richard C., Richard Barrutia, e Anna Uhl Chamot. English for International Communication. Teacher´s Edition.
Citatione MLA (8a ed.)Yorkey, Richard C., et al. English for International Communication. Teacher´s Edition.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.