THE EFFECT OF TIME OF EXPOSURE TO SULPHUR DIOXIDE ON POTASSIUM LOSS FROM AND PHOTOSYNTHESIS IN THE LICHEN, CLADINA RANGIFERINA (L.) HARM. - Tomassini, F. D.; Lavoie, P.; Puckett, K. J.; Nieboer, E.; Richardson, D. H. S. (New Phytologist, 1977)