Module:fi-nominals
Fragment of a discussion from User talk:Rua
Internetters do whatever is easiest without knowing right from wrong, but newspapers and book publishers use the apostrophe. I must confess that I didn't know that there's a difference until recently. I modified the templates myself - your code is clear enough to figure out what to change. I'm in the process of rooting out the printer's apostrophe from the Finnish entries.