Columbia subject headings:
Architects--Germany--Correspondence.
Persius, Ludwig, 1803-1845--Correspondence.
Persius, Ludwig, 1803-1845.
Harvard subject headings:
Architecture--Germany--Designs and plans.
Architecture--Germany--Sources.
Persius, Ludwig, 1803-1845--Correspondence.
Princeton subject headings:
Architecture--Germany--Designs and plans.
Architecture--Germany--Sources.
Persius, Ludwig, 1803-1845--Correspondence.