Columbia subject headings:
Puerto Rico--Politics and government--1898-1952.
Puerto Rico--Politics and government--1952-1998.
Puerto Rico--Relations--United States.
United States--Relations--Puerto Rico.
Harvard subject headings:
Puerto Rico--Politics and government--1898-1952.
Puerto Rico--Politics and government--1952-
Puerto Rico--Relations--United States.
United States--Relations--Puerto Rico.
Princeton subject headings:
Puerto Rico--Politics and government--1898-1952.
Puerto Rico--Politics and government--1952-1998.
Puerto Rico--Relations--United States.
United States--Relations--Puerto Rico.