United States. National Capital Park and Planning Commission. (1950). Open spaces and community services: A portion of the comprehensive plan for the national capital and its environs. The Commission.
Trích dẫn kiểu Chicago (xuất bản lần thứ 7)United States. National Capital Park and Planning Commission. Open Spaces and Community Services: A Portion of the Comprehensive Plan for the National Capital and Its Environs. Washington: The Commission, 1950.
Trích dẫn kiểu MLA (xuất bản lần thứ 8)United States. National Capital Park and Planning Commission. Open Spaces and Community Services: A Portion of the Comprehensive Plan for the National Capital and Its Environs. The Commission, 1950.
Cảnh báo: Các trích dẫn này có thể không phải lúc nào cũng chính xác 100%.