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Barrows, David P. (1916). "The Governor-General of the Philippines Under Spain and the United States". The American Historical Review. 21 (2): 288–311. doi:10.2307/1835051. JSTOR1835051.
"List of Provinces". PSGC Interactive. Makati City, Philippines: National Statistical Coordination Board. Archived from the original on January 17, 2013. Retrieved October 17, 2013.
"List of Provinces". PSGC Interactive. Makati City, Philippines: National Statistical Coordination Board. Archived from the original on January 17, 2013. Retrieved October 17, 2013.