Columbia subject headings:
Equality--Mexico--Congresses.
Equality--Spain--Congresses.
Political rights--Mexico--Congresses.
Political rights--Spain--Congresses.
Right to education--Mexico--Congresses.
Right to education--Spain--Congresses.
Harvard subject headings:
Equality--Mexico--Congresses.
Equality--Spain--Congresses.
Mexico--Social conditions--1970---Congresses.
Political rights--Mexico--Congresses.
Political rights--Spain--Congresses.
Right to education--Mexico--Congresses.
Right to education--Spain--Congresses.
Spain--Social conditions--1975---Congresses.
Princeton subject headings:
Mexico--Social conditions--1970---Congresses.
Spain--Social conditions--1975---Congresses.