References from the California Lichen Catalog

BREUSS, O. 2002.

Catapyrenium, pp. 125–128; Clavascidium, pp. 158–159; Endocarpon, pp. 181–187; Placidiopsis, pp. 383–384; Placidium, pp. 393–394; Placopyrenium, pp. 394–397; Thrombium, pp. 483–484, in T. H. Nash III, B. D. Ryan, C. Gries, & F. Bungartz (eds.), Lichen flora of the Greater Sonoran Desert region, Vol. 1. Lichens Unlimited, Arizona State University, Tempe.