In my research into the history and art of my ancestors, a wealth of information has come from Loit Joekalda of Estonia. He believes the best researcher of the rock art of the Fenno-Ugrians is Väinö Poikalainen, chair of the Estonian Society of Prehistoric Art**, of Tarto, Estonia. The society publishes papers on rock art and folklore to Folklore.

Poikalainen wrote a book review about KALLIOKUVAT KERTOVAT (Pictures on rock are telling) by Pekka Kivikäs (Atena kustannnus oy, 2000. 124 pp. In Finnish.) He writes:

The art teacher Pekka Kivikäs has become well-known for his work as an active documenter and publisher of Finnish rock paintings… the book is aimed at the wide circle of readers interested in the ancient culture of Finno-Ugric regions…Kivikäs considers rock art the silent message of man from behind the thousands of years, to perceive which one needs to relax, listen and see. When we loose the ability to do this, we also loose[sic] the possibility to perceive those near us and our environment.

Folklore has also printed an article by Kivik&#228s (PDF) on the subject.
UPDATE: March 21.05 **link no longer active