R. Wicander and G. Playford, “Organic-walled microphytoplankton assemblage of the Middle Devonian (Givetian) Arkona, Hungry Hollow and Widder formations, Ontario, Canada: biostratigraphic and palaeogeographic significance”, Bol. geol. min., vol. 128, no. 4, pp. 839–883, Dec. 2017.