1. Beichman, C. A., Neugebauer, G., Habing, H. J., Clegg, P. E., and Chester, T. J.: 1985,Infrared Astronomical Satellite Catalogs and Atlases, Explanatory Supplement.
2. Bohren, C. F. and Huffman, D. R.: 1984,Absorption and Scattering of Light by Small Particles, John Wiley and Sons, New York.
3. Cohen, M.: 1980,Monthly Notices Roy. Astron. Soc. 191, 499.
4. Day, K. L.: 1974,Astrophys. J. 192, L15.
5. Day, K. L.: 1979,Astrophys. J. 234, 158.