Philippines (Republic) Office of Manpower Services. Employment Service Division. (1957). Philippine occupational classification with titles, codes and definitions. s.n.
Chicago-referens (17:e uppl.)Philippines (Republic) Office of Manpower Services. Employment Service Division. Philippine Occupational Classification with Titles, Codes and Definitions. 224p.,Manila: s.n, 1957.
MLA-referens (9:e uppl.)Philippines (Republic) Office of Manpower Services. Employment Service Division. Philippine Occupational Classification with Titles, Codes and Definitions. s.n, 1957.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.