SIMBAD references

We report V photometry of three RS CVn stars-HK Lac, SZ Psc, and l And-from the AAVSO photoelectric photometry program, and from transformed Hipparcos photometry, over 3500 days. Eighteen photoelectric photometry observers contributed to this project. The stars vary on periods of days to weeks, due to rotation of a spotted photosphere. The rotational light curves vary on time scales of months to years, due to changes in the area and/or distribution of the spots.