1. Carbon, D. F. and Gingerich, O.: 1969, in O. Gingerich (ed.),Theory and Observation of Normal Stellar Atmospheres, MIT Press, Cambridge, p. 377.
2. Cester, B., Giurichin, G., Mardirossian, F., and Pucillo, M.: 1977,Astron. Astrophys. Suppl. 30, 223.
3. Fehrenbach, Ch., Duflot, M., Boulon, J., Rebeirot, E., and Lanoe, C.: 1966,Publ. Obs. de Haute Provence 8, 289.
4. Frank, F.: 1985,BAV Mitt., No. 36.
5. Giannone, P. and Giannuzzi, M. A.: 1974,Astrophys. Space Sci. 26, 289.