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2. A. Yamamoto: Climatology of the Traffic Accident in Japan on the Expressway with Dense Fog and a Case Study (Meteorological Research Institute, 2001).
3. A. Yamamoto: J. Jpn. Soc. Natural Disaster Sci. 19 (2000) 99 [in Japanese].
4. H. C. Van de Hulst: Light Scattering by Small Particle (John Wiley & Sons, New York, 1957).
5. J. S. Dubuisson: Road Visibility in Fog, International Commission on Illumination (2005).