Hirnantia sagittifera (Brachiopoda) and Mucronaspis mucronata s.l. (Trilobita) in the Upper Ordovician of the East Baltic : taxonomy and distributionHints, Linda; Pärnaste, Helje; Gailite, Lilita-IlgaEstonian journal of earth sciences2012 / p. 65-81 : ill https://www.researchgate.net/publication/258439664_Hirnantia_sagittifera_Brachiopoda_and_Mucronaspis_mucronata_sl_Trilobita_in_the_Upper_Ordovician_of_the_East_Baltic_Taxonomy_and_distribution