(1972). Population and heirarchy of cities and municipalities: Bicol region. [s.n.].
Chicago-viite (17. p.)Population and Heirarchy of Cities and Municipalities: Bicol Region. [Manila]: [s.n.], 1972.
MLA-viite (9. p.)Population and Heirarchy of Cities and Municipalities: Bicol Region. [s.n.], 1972.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.