Here's the days from Monday to Friday per this site:

http://www.hut.fi/~tkvopint/topiusage.html

Maanantai      Monday 
Tiistai Tuesday
Keskiviikko Wednesday
Torstai Thursday
Perjantai Friday

Wednesday looks like it might be a loan translation from the German Mittwoch. Well, part loan translation part loan word. Who knows where they got that Perjan for Friday!