Columbia subject headings:
Catholic Church. Populorum progressio.
Church and social problems--Catholic Church.
Developing countries.
Harvard subject headings:
Catholic Church. Pope (1963-1978 : Paul VI). Populorum progressio
Church and social problems--Catholic Church
Developing countries.
Princeton subject headings:
Catholic Church. Pope (1963- : Paulus VI). Populorum progressio.
Church and social problems--Catholic Church.
Developing countries.