Columbia subject headings:
Hesse, Hermann, 1877-1962--Correspondence.
Machemehl, Günter, 1911-1970--Correspondence.
Harvard subject headings:
Hesse, Hermann, 1877-1962.--Correspondence.
Machemehl, Günter, 1911-1970--Correspondence.
Princeton subject headings:
Hesse, Hermann, 1877-1962. Correspondence.
Machemehl, Günter, 1911-1970--Correspondence.