Assessing the quality of Baltoscandian chitinozoan biozones using quantitative stratigraphy [Online resource]Hints, Olle; Antonovitš, Liina; Nõlvak, Jaak; Liang, YanTrekking Across the GOBE : From the Cambrian through the Katian, June 3-7, 2018 : program & abstracts2018 / p. 39 https://igcp653athens2018.files.wordpress.com/2018/05/conference-programabstracts-sm1.pdf Morphological variation of chitinozoans : a case study from the Upper Ordovician Viola Springs Formation, Arbuckle Mountains, Oklahoma, USA [Online resource]Liang, Yan; Nõlvak, Jaak; Goldman, Daniel; Hints, OlleTrekking Across the GOBE : From the Cambrian through the Katian, June 3-7, 2018 : program & abstracts2018 / p. 45 https://igcp653athens2018.files.wordpress.com/2018/05/conference-programabstracts-sm1.pdf