Protection of the geosites and the monograph "Estonian ancient natural monuments"Pirrus, Enn-Aavo; Raudsepp, ReinProGEO '97. Brochure of abstracts : the Second General Assembly of the European Association for the Conservation of the Geological Heritage : scientific conference : Tallinn-Lahemaa National Park, June 2nd-4th, 19971997 / p. 9