Can you help me to find books about handicapped persons/students in Finland? In english or german! Thanks!

You are right - it isn't easy to find material in English on handicapped/disabled people in Finland. Something, however, can be found on the Internet, though most sites are only in Finnish and Swedish. You don't specify what sort of information you need or for what purpose, but I will try to give you some links:
http://www.invalidiliitto.fi/in_english.html, http://193.209.217.5/in/internet/english.nsf/NET/081101144154EH?openDoc…, http://www.stm.fi/Resource.phx/eng/subjt/socwe/disab/index.htx, http://www.tilastokeskus.fi/index_en.html
(for statistics). There is also an association of disabled people called Kynnys (Threshold). Their website, at http://www.kynnys.fi/, is unfortunately only in Finnish, but you can surely contact them directly by e-mail, see page Yhteystiedot. All the other links also contain contact details for further information. As for books in English on the subject, they also seem to be very scarce and probably impossible to get in Germany. I therefore strongly recommend the websites above!