Columbia subject headings:
Pereyra, Carlos, 1871-1942--Correspondence.
Reyes, Alfonso, 1889-1959--Correspondence.
Harvard subject headings:
Princeton subject headings:
Authors, Mexican--20th century--Correspondence.
Historians--Mexico--20th century--Correspondence.
Pereyra, Carlos, 1871-1942--Correspondence.
Personal correspondence.
Reyes, Alfonso, 1889-1959--Correspondence.