Tài liệu tham khảo WikiPedia: Olongapo http://www.sangunian.com http://members.tripod.com/Olongapo/legend.html //tools.wmflabs.org/geohack/geohack.php?language=v... http://www.census.gov.ph/data/pressrelease/2009/pr... http://www.olongapocity.gov.ph/
