The project she did in Vienna is really quite remarkable - I hope I'll manage to explain its conceptual makeup lucidly enough: she casted the negative space of a library room, that is, not your usual perception of library shelves with the books' bindings and titles in front of you, but rather the view from the other side - it is the pages we are confronted with. Where is this work and what is it meant to commemorate? It is in the Judenplatz in Vienna, a square where the Jews were gathered under the Nazi rule before being shipped to the camps.
The people to whom this memorial is dedicated are thus portrayed as books - their stories now being permanently shelved within the historical discourse. I would also suggest that the concept of the 'library catalog' is employed here - just think of the numbers and overall "cataloging" that the Nazi prisoners were subjected to.
The books are also the first to be persecuted under the regime - it is the burning of books that usually precipitates the burning of the bodies.