Template:Scheidegger & Schultz, 2004
- Scheidegger, C. & Schultz, M. 2004. Harpidium. Pages 133–134. In Nash, T.H., III, Ryan, B.D., Diederich, P., Gries, C. & Bungartz, F. (eds.), Lichen Flora of the Greater Sonoran Desert Region. Volume II (most of the microlichens, balance of the macrolichens, and the lichenicolous fungi). 742 pages. Lichens Unlimited, Arizona State University, Tempe, Arizona. ISBN 0971675910