G.F.W. Herngreen, J.H.A. van Konijnenburg - van Cittert and H.W. Oosterink 2005. New geological data (Middle Triassic, Rhaetian-Liassic and Oligocene) of the Winterswijk quarry, the eastern Netherlands. Netherlands Journal of Geosciences. 84, (Dec. 2005), 409 - 413. DOI:https://doi.org/10.1017/S0016774600021223.