P. L.  Nimis, The Lichens of Italy: An annotated catalogue, vol. 12. Torino: , 1993.

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

M.  Schultz, ?Studies on Lichens from southern Yemen (Arabian Peninsula)?, The Lichenologist, vol. 30, pp. 293-297, 1998.

G.  Brown, ?Saxicolous and terricolous lichens from the foothills of northern Oman?, Nova Hedwigia, vol. 75, pp. 177-188, 2002.

T. H.  Nash_, III, Ryan, B. D., Gries, C., and Bungartz, F., Lichen Flora of the Greater Sonoran Desert Region, vol. 1. Tempe: Lichens Unlimited, 2001.

M.  Schultz, ?The saxicolous and terricolous, cyanobacterial lichens of Socotra (Yemen, Indian Ocean)?, Nova Hedwigia, vol. 77, pp. 73-97, 2003.

?Index Fungorum [taxonomy information]?, 2008.

T.  H. Lumbsch and Huhndorf, S. M., ?Outline of Ascomycota - 2007. [Classification Information]?, Myconet, vol. 13, pp. 1-58, 2007.