Philippines. National Mapping and Resource Information Authority. Province of Abra (Ed.1, September, 1990.). National Mapping and Resource Information Authority, 1990.
Citação do estilo Chicago (17ª ed.)Philippines. National Mapping and Resource Information Authority. Province of Abra. Ed.1, September, 1990. Makati, Metro Manila: National Mapping and Resource Information Authority, 1990.
Citação MLA (9ª ed.)Philippines. National Mapping and Resource Information Authority. Province of Abra. Ed.1, September, 1990. National Mapping and Resource Information Authority, 1990.
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