J. Walter Thomson and Brehmer, B., American Arctic Lichens I. The Macrolichens. Columbia University Press, 1984.

O.  Gilbert, Lichens. London: HarperCollins, 2000, p. 288.

P. M.  McCarthy, ?Checklist of the Lichens of Australia and its Island Territories?, Australian Biological Resources Study, Canberra., 2010.

?Index Fungorum [taxonomy information]?, 2008.