Tài liệu tham khảo WikiPedia: Cái_Vồn //tools.wmflabs.org/geohack/geohack.php?language=v... http://www.gso.gov.vn/phuong-phap-thong-ke/danh-mu... http://moc.gov.vn/vn/tin-tuc/1173/5128/cong-nhan-t... https://thuvienphapluat.vn/van-ban/Bo-may-hanh-chi...