Perhaps you should try some spelling variations:
private collections » private corporations
23 bibliography » 3 bibliography, 22 bibliography, 2.7 bibliography
13 bibliography » 11 bibliography, 3 bibliography, 12 bibliography
co catalogs » _ catalogs, e catalogs, coins catalogs
12 private » 2 private, 1 private, 3 private
11 germany » 11 german, 1918 germany, 7 germany
21 berlin » 1 berlin, 2 berlin, 2015 berlin

Try widening your search to All Fields.

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• The words AND, OR and NOT may confuse the search; try adding quotes: "%22humanities %((23 bibliography) OR (13 bibliography)) %12 private collections %11 germany %21 berlin %co catalogs%22".
• Adding a wildcard symbol may retrieve word variants: %22humanities %((23 bibliography) OR (13 bibliography)) %12 private collections %11 germany %21 berlin %co catalogs%22*.