B.  Büdel, Elix, J. A., and Kappen, L. (ed.), ?Peltula langei Büdel et Elix spec. nov. from Australia, with remarks on its chemistry and the ascoma of Peltula clavata (Krempelh.) Wetm.?, in New Species and Novel Aspects in Ecology and Physiology of Lichens. In Honour of O. L. Lange, Berlin: , 1997, pp. 3-9.

M.  Schultz, Porembski, S., and Büdel, B., ?Diversity of Rock-Inhabiting Cyanobacterial Lichens: Studies on Granite Inselbergs along the Orinoco and in Guyana?, Plant Biology, vol. 2, pp. 482-495, 2000.