Percentage of Higher Education Institutions Offering Distance Education. US Department of Education.
Цитирование в стиле Чикаго (17-е изд.)Percentage of Higher Education Institutions Offering Distance Education. US Department of Education.
Цитирование MLA (8-е изд.)Percentage of Higher Education Institutions Offering Distance Education. US Department of Education.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.