1. Allen, C.W.: 1973, Astrophysical Quantities ( 3rd ed.; London; Athlone).
2. Ando, H.: 1976, Publ. astr. Soc. Japan, 28, 517.
3. Asian, Z.: 1973, Monthly Notices Roy. Astr. Soc. 165, 337.
4. Bateson, F.M., and Wood, P.R.: 1980, Publ. Variable Star Section, Roy. Astr. Soc. New Zealand, in press.
5. Baud, G.: 1978, OH/IR Stars in the Galaxy, Leiden.