Of course, the guidelines of the Public Health Authority apply, meaning not to go out with symptoms or close contact with the infected. See Recommendations due to the corona virus, Covid-19 for information from Södertörn University (news article, updated regularly).
Keep a distance of 1,5 meters to other people, visitors as well as members of staff. Wash your hands or use hand sanitizer before entering and leaving.
Reemember to keep a distance while awaiting your turn. No more than 2 persons are allowed at the same time in the copy rooms.
Update 24 November: Group studies
Don't work in groups at the library. If you need to, you may continue to use the study environment, but only for solo studies.