Tài liệu tham khảo WikiPedia: Nậm_Ngừm http://www.wepa-db.net/policies/state/laos/river.h... http://www.adb.org/Documents/ADBBO/CSRN/Uploads/40... https://www.google.com/maps/@18.61053,102.7353171,... https://commons.wikimedia.org/wiki/Category:Rivers...