"About a quarter of social science students at a (deliberately chosen left-leaning) university in Frankfurt, Germany, are in favour of removing controversial books about certain topics from their university library."
ETA: And, in fairness to pg, the sentence quoted ("Roughly one-third of students are also in favor of banning controversial books from their university library") is in fact a direct quote from the study.
This is false.
This is presumably about Hitler's "Mein kampf". Which wasn't banned by law in Germany. The province of Bavaria simply inherited the ownership (copyright) of it and decided not to grant anyone permission to print it. Thats why it was not illegal to have the book but it was illegal to print it.
I believe the copyright has now expired in Germany and it is in the public domain.
Mein Kampf itself is legal. But not everything is.