John W.M. Jagt. “Cyathidium Vlieksi, a New Holopodid Crinoid from the Upper Maastrichtian (Late Cretaceous) of Southern Limburg, The Netherlands”. Netherlands Journal of Geosciences, Jan. 1986, pp. 215-21, https://njgjournal.nl/index.php/njg/article/view/13144.