Clarifying Haljala Stage in EstoniaPaiste, Tõnn; Meidla, Tõnu; Männik, Peep; Nõlvak, Jaak13th International Symposium on the Ordovician System, July 19-22, 20192019 / p. 149–150 http://www.igcp653.org/wp-content/uploads/2019/07/ISOS13Proceedings.pdf