For more information on this species see:
Plantlife Species Dossier:
http://www.plantlife.org.uk/uk/assets/saving-species/saving-species-dossier/Heterodermia_leucomelos_dossier.pdf
For more information on British lichens see:
Dobson, F. (2000) Lichens. An illustrated guide to the British species. The Richmond Publishing Co. Ltd., Slough.