Philippines. National Economic and Development Authority. Regional Development Council, Region I. (1976). Demographic profile on Region I: A study on population growth, composition and employment. The Council.
Lua i Stíl Chicago (17ú heag.)Philippines. National Economic and Development Authority. Regional Development Council, Region I. Demographic Profile on Region I: A Study on Population Growth, Composition and Employment. San Fernando, La Union: The Council, 1976.
Lua MLA (9ú heag.)Philippines. National Economic and Development Authority. Regional Development Council, Region I. Demographic Profile on Region I: A Study on Population Growth, Composition and Employment. The Council, 1976.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.