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M.  Powell and Cannon, P., ?Hypotrachyna afrorevoluta and H. revoluta are both widespread in Britain but do we know how to identify them??, British Lichen Society Bulletin, vol. 112, pp. 36-39, 2013.

M.  Powell and Vondrák, J., ?Caloplaca citrina and C. lactea are incorrectly understood in the British Isles?, British Lichen Society Bulletin, vol. 109, pp. 25-30, 2011.

M.  Powell and Vondrák, J., ?Yellow sorediate crusts called "Caloplaca citrina" in England?, British Lichen Society Bulletin, vol. 110, pp. 20-24, 2012.

M.  Powell and Vondrák, J., ?Italian balustrade at Cliveden hosts Italian lichens??, British Lichen Society Bulletin, vol. 110, pp. 11-14, 2012.