Suomea Suomeksi study book comes together with a small dictionary-like booklet. I think there is a version translated into Serbian too. I for sure know there is a Chroation one... May be you can get in contact with the Helsinki University international students community. I knew a few serbs who were studying there few years back. And for sure there are some now. You could probably ask them to get the book for you and hand it over when they come back to Serbia.
Good luck
