Chitinozoan response to a gigantic Late Ordovician volcanic ash fall recorded in northern EstoniaHints, Olle; Bauert, Garmen; Grigorjeva, Irina; Nõlvak, Jaak; Meidla, Tõnu; Perrier, Vincent10th Baltic Stratigraphic Conference : Checiny, 12-14 September 2017 : abstracts and field guide2017 / p. 34-35 http://geo.uw.edu.pl/tl_files/publikacje/10th_Baltic_Stratigraphic_Conference_Abstracts_and_Field_Guide.pdf