1. Arizona Department of Environmetnal Quality, 1986. Air Quality Management internal memo: Document # FRQ-AQ-1240. Permit # 1000052. Ajo, New Cornelia. Regional ADEQ Office,.Phoenix, Arizona.
2. Arizona Department of Environmetnal Quality, 1995. 1994 Air quality data for Arizona. EQR 95-2. Phoenix, Arizona.
3. Assessment of metal air pollution by epiphytic lichens;Bargagli;Studia Geobotanica,1990
4. The relationship between cadmium uptake and heavy metal tolerance in the lichen genus Peltigera;Beckett;New Phytologist,1984
5. Statistical baseline values for chemical elements in the lichen Hypogymnia physodes;Bennett,2000