Is there a library I can use in holidays (sundays)? I'm looking for library which keeps library (more exactly, study room: not wanting to chech out books) open and located near Kamppi or Pasila.
Helsinki City Libraries open on Sundays are:
Cable Book Library
Opening hours, contact information and location on map:
Cable Book Library is near Kamppi, but there isn't any study room.
Itäkeskus library has a study room (for 48 persons), but the library is in East-Helsinki.
Kallio (study room for 8 persons) and Töölö (study room for almost 100 persons) Libraries are both quite near Pasila so perhaps You'll find other or both of them suitable for Your purposes.