Covey, S. R. (1999). Seven habits of highly effective people (1st.). Pocket books.
Chicago-стиль цитированияCovey, Stephen R. Seven Habits of Highly Effective People. 1st. London: Pocket books, 1999.
MLA-цитированиеCovey, Stephen R. Seven Habits of Highly Effective People. 1st. Pocket books, 1999.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.