Dyulgerov N. (1989). Nature protection is a social necessity: Chairman of the Commit. for environ. Protection at the Council of Ministers of the People's Republic of Bulgaria. Пресс.
Цитирование в стиле Чикаго (17-е изд.)Dyulgerov N. Nature Protection Is a Social Necessity: Chairman of the Commit. for Environ. Protection at the Council of Ministers of the People's Republic of Bulgaria. София: Пресс, 1989.
Цитирование MLA (8-е изд.)Dyulgerov N. Nature Protection Is a Social Necessity: Chairman of the Commit. for Environ. Protection at the Council of Ministers of the People's Republic of Bulgaria. Пресс, 1989.
Предупреждение: эти цитированмия не могут быть всегда правильны на 100%.