Columbia subject headings:
Harvard subject headings:
Gruber, L. Fritz--Art collections--Exhibitions.
Photography, Artistic--Exhibitions
Photography, Artistic--Private collections--Germany--Exhibitins.
Princeton subject headings:
Gruber, L. Fritz--Photograph collections--Exhibitions.
Photograph collections--Germany--Cologne--Exhibitions.
Photography, Artistic--Exhibitions.
Photography, Artistic--Private collections--Germany--Cologne--Exhibitions.
Portrait photography--Exhibitions.