http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Cuốn sách giới thiệu toàn bộ lịch sử hình thành và phát triển của hệ thống thành lũy trên mảnh đất 1000 năm lịch sử