Subcommission on Devonian Stratigraphy :  fossil groups important for boundary definition / 
P. Bultynck (editor) ;  International Union of Geological Sciences Subcommission on Devonian Stratigraphy. 
 - Frankfurt a.M. :  Senckenbergische Naturforschende Gesellschaft,    2000. 
<br/><br/><label>Subjects--Index Terms: </label>გეოლოგია სტრატიგრაფია