The breakthrough song for Kirka was "Hetki lyö" (The moment strikes), published as a single in the autumn of 1967. It was officially done by the group D'Islanders, but the song was chosen espcially for Kirka to sing, and today it's solely remembered as Kirka's song. In those times D'Islanders was working as the backing group for Danny. And in fact it was Danny who picked up this song for Kirka. The original one was a small hit (and one of their last ones) for The McCoys in the spring of 1967 and was called "Beat The Clock". It was written by the band's producer, Richard Goettehrer.
Here's the pair:
9 minutes ago