"Province: ILOCOS SUR". PSGC Interactive. Makati City, Philippines: National Statistical Coordination Board. Archived from the original on 24 November 2007. Retrieved 23 September 2013.
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"Province: ILOCOS SUR". PSGC Interactive. Makati City, Philippines: National Statistical Coordination Board. Archived from the original on 24 November 2007. Retrieved 23 September 2013.