Cita APA (7th ed.)

(1968). Steps to spoken english: A graded course for spanish-speaking. Longman.

Cita Chicago (17th ed.)

Steps to Spoken English: A Graded Course for Spanish-speaking. London: Longman, 1968.

Cita MLA (9th ed.)

Steps to Spoken English: A Graded Course for Spanish-speaking. Longman, 1968.