Jets, man, your band - 'specially the one that did Monson - seems to be a relative of the earlier in the 40s - 60s) so common type of Finnish dance quartet: a man, an accordion, a stool and a bottle (or trio if the stool was left out).

That Digelius site given by Lepus Rex IS worth visiting, at least their Finnish selection seems to me quite comprehensive, as much as folk music is concerned.

AKS