1. Bartoli, A., Cardarelli, E., Achilli, M., Campanella, L., and Massari, G., 1994: Biomonitoraggio dell?aria di Roma: accumulo di metalli pesanti in trapianti di licheni, Ann. Bot. LII(11), 239?266.
2. Betinelli, M., Spezia, S., and Bizzarri, G., 1996: Trace element determination in lichens by ICP-MS, At. Spectrosc. 17, 133?141.
3. Caniglia, G., Calliari, I., Celin, L., and Tollardo, A. M., 1994: Metal determination by EDXFR in lichens. A contribution to pollutants monitoring, Biol. Trace Elem. Res. 43?45, 213?221.
4. Cercasov, V., Pantelic?, A., S?l?gean, M., Caniglia, G., and Scarlat, A., 2002: Comparative study of the suitability of three lichen species to trace-element air monitoring, Environ. Pollut. 119, 129?139.
5. Conti, M. E., 2002: Il monitoraggio biologico della qualit� ambientale, SEAM Editor, Rome, 181 pp.