Cita APA (7th ed.)

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

Cita Chicago (17th ed.)

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

Cita MLA (9th ed.)

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