Cladonia: a field guide

The author writes: "Cladonia is an extensive and difficult genus of lichens, but one that is extremely valuable in defining many plant communities, particularly heathlands. There is therefore a need for a fairly simple field guide for the use of the nonspecialist. The original idea of writing this guide came about because I was having great difficulty identifying the species in the field and grew tired of having to collect copious specimens for later determination. A “first draft” was produced, which was distributed to whoever expressed an interest, mostly NCC personnel. This was a very rough and ready document, and clearly needed a great deal of modification, so this revised version was written.
N. G. Hodgetts
Available as: 
Lichen Lichens