I recommend anyone interested to look at some of the documentation done in the IANA timezone dataset (historical references of Finland shown here): https://gith

I recommend anyone interested to look at some of the documentation done in the IANA timezone dataset (historical references of Finland shown here): https://github.com/eggert/tz/blob/master/europe#L1213 https://github.com/eggert/tz/blob/master/europe#L1213