van Konijnenburg-van Cittert, J. H., V. Mikuž, and J. Pavšič. “Pterophyllum (Cycadopsida) from Carnian Beds in Poljane Valley (Slovenia)”. Geologija, vol. 44, no. 2, Dec. 2001, pp. 317-23, doi:10.5474/geologija.2001.023.