Citazione Stile APA (7a Edizione)

(1977). Building English skills: Blue level. Skills practice book. McDougal, Littell & Company.

Citazione stile Chigago Style (17a edizione)

Building English Skills: Blue Level. Skills Practice Book. Evanston, Illinois, USA: McDougal, Littell & Company, 1977.

Citatione MLA (9a ed.)

Building English Skills: Blue Level. Skills Practice Book. McDougal, Littell & Company, 1977.