Philippines (Republic) Office of Manpower Services. Employment Service Division. (1957). Philippine occupational classification with titles, codes and definitions. s.n.
Cita Chicago (17th ed.)Philippines (Republic) Office of Manpower Services. Employment Service Division. Philippine Occupational Classification with Titles, Codes and Definitions. 224p.,Manila: s.n, 1957.
Cita MLA (9th ed.)Philippines (Republic) Office of Manpower Services. Employment Service Division. Philippine Occupational Classification with Titles, Codes and Definitions. s.n, 1957.
Atenció: Aquestes cites poden no estar 100% correctes.