1. See, for example, Proc. NATO Expert Conf. on Laser Spectroscopy of the Atmosphere, Opt. Quantum Electr. 8 (1976); E. D. Hinkley, K. W. Nill, F. A. Blum: Laser Focus, pp. 47–51 (April 1976) ; E. D. Hinkley, R. T. Ku, K. W. Nill, J. F. Butler: Appl. Opt., in press
2. T. H. Maugh, II: Science 177, 1090 (1972)
3. J. A. Hodgeson, W. A. McClenny, P. L. Hanst: Science 182, 248 (1973)
4. J. A. Hodgeson, W. A. McClenny, P. L. Hanst: Proc. Int. Conf. on Environmental Sensing and Assessment, Las Vegas, Nevada (September 14–19, 1976)
5. J. N. Pitts Jr., B. J. Finlayson: Ang. Chem. (Int. Ed.) 14, 1 (1975), and references therein.