Seal of the Province of Bulacan
National Historical Commission of the Philippines - Heraldry Division, SVG remake by Trajano Dagala C.
<p>From the Symbols of the State Republic of the Philippines, Bureau of Local Government, Dept. of Local Government and Community Development, 1975
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<a rel="nofollow" class="external free" href="https://archive.org/details/SymbolsOfTheStateRepublicOfThePhilippines/page/n189">https://archive.org/details/SymbolsOfTheStateRepublicOfThePhilippines/page/n189</a>