I read about the
fights between Perun and Veles in books on Slavic mythology. I never
knew original sources on mythological stories. The legends are stories of people passed from generation to generation since ancient times.
I read another Belarusian legend that describes a dragon who
fears thunder and likes a girl helping her family, and the release of rain after the
dragon was defeated by thunder (Perun).
I can probably find a picture of a Valun (big stone) in Belarus called dragon stone. Large stones (valuns) are important part of our mythology.