1. Hayakawa, S., Ito, K., Matsumoto, T., and Uyama, K.: 1977, Astron. Astrophys. 58, 325
2. Hayakawa, S., Matsumoto, T., Murakami, H., Uyama, K., Thomas, J.A., and Yamagami, T.: 1981, Astron. Astrophys. 100, 106
3. Kawara, K., Kozasa, T., Sato, S., Kobayashi, Y., and Okuda, H.: 1982, Pub. Astron. Soc. Japan 34, 389
4. Maihara, T., Oda, N., Sugiyama, T., and Okuda, H.: 1978, Publ. Astron. Soc. Japan 30, 1
5. Okuda, H.: 1981, in “Infrared Astronomy”, IAU Symp. No. 96, review p. 247.