Actually, the regrettable fate of organized civilian UFO research in Finland has been a split into two associations, namely the older FUFORA (Suomen Ufotutkijat ry) and the newer UFO-Finland (apparently trying to line up with the rest of similiar associations in the world, like your UFO-Sverige in Sweden...)
Koivula, being the chairman of the former, has been recently accused of applying unscientific methods in his investigations. However, I see this problem merely as an old internal schism plaguing all ufology... (I don't think this "scientifical" branch is so well defined, anyway.)
The most recent (big) case in which Koivula participated, is this video claimed to be recorded by some Finnish border/coast guard officials:
http://www.suomenufotutkijat.fi/infraredvideo.htm (website in English)
And for that literature written by Koivula, perhaps you should contact FUFORA by e-mail:
info@suomenufotutkijat.fi