Lancion, Conrado M. Jr. (1995). "The Provinces; Lanao del Sur". Fast Facts about Philippine Provinces. cartography by de Guzman, Rey (The 2000 Millennium ed.). Makati, Metro Manila, Philippines: Tahanan Books. pp. 94–95. ISBN971-630-037-9. Retrieved December 25, 2015.
Autonomous Region in Muslim Mindanao, Department of Agriculture: Lanao del SurArchived January 19, 2015, at the Wayback Machine (There are major discrepancies among authoritative sources: 4121.3 km² (NAMRIA); 1,349,437 ha (NSCB, this value seems unreasonable and must be assumed as erroneous, see Talk:Lanao del Sur#Area))
Autonomous Region in Muslim Mindanao, Department of Agriculture: Lanao del SurArchived January 19, 2015, at the Wayback Machine (There are major discrepancies among authoritative sources: 4121.3 km² (NAMRIA); 1,349,437 ha (NSCB, this value seems unreasonable and must be assumed as erroneous, see Talk:Lanao del Sur#Area))