Reference
Robert Reiter, Roman Türk, T.G.Allan Green, Burkhard Schroeter (2007): Photosynthesis of Three Umbilicaria Species from Lichen-Dominated Communities of the Alpine/Nival Belt of the Alps Measured Under Controlled Conditions. – Phyton, Annales Rei Botanicae, Horn – 46_2: 247 - 258.