1. Fröhlich C., Brusa R. W., paper presented at the Solar Constant Workshop, Big Bear, California, 19 to 21 May;
2. Labs D., Neckel H., Solar Phys. 19, 3 (1971).
3. Crawford D. L., Barnes J. V., Astron. J. 75, 978 (1971).
4. Jerzykiewicz M. unpublished data.
5. Lockwood G. W. unpublished data.