"List of Provinces". PSGC Interactive. National Statistical Coordination Board. Archived from the original on April 19, 2016. Retrieved August 2, 2022.
officialgazette.gov.ph
Commonwealth of the Philippines (February 8, 1935). "The 1935 Constitution". Official Gazette of the Republic of the Philippines. Retrieved November 18, 2017.
"List of Provinces". PSGC Interactive. National Statistical Coordination Board. Archived from the original on April 19, 2016. Retrieved August 2, 2022.