Columbia subject headings:
Harvard subject headings:
Architects--France--Correspondence.
Architecture--France--20th century.
Le Corbusier, 1887-1965--Correspondence.
Perret, Auguste, 1874-1954--Correspondence.
Ritter, William, 1867-1955--Correspondence.
Princeton subject headings:
Architects--France--Correspondence.
Le Corbusier, 1887-1965--Correspondence.