(1969). Steps to spoken english: A graded course for spanish-speaking students. Longman.
Цитирование в стиле Чикаго (17-е изд.)Steps to Spoken English: A Graded Course for Spanish-speaking Students. London: Longman, 1969.
Цитирование MLA (9-е изд.)Steps to Spoken English: A Graded Course for Spanish-speaking Students. Longman, 1969.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.