The largest organization for variable stars: provides professional and amateur collaboration, research, and analysis of variable star observations.

Research group working on the GCVS, Sternberg Astronomical Institute, Moscow, Russia. Includes catalogs and publications.

The IBVS is a bulletin of Commissions 27 and 42 of the International Astronomical Union, published by Konkoly Observatory, Budapest, Hungary.

Collaborative Project aimed at getting new people involved in variable star observing.

ASSA's variable star group. News, FAQ, charts, and software.

Currently contains 311 stars which have been classified as Delta Scutis or Gamma Doradus in some published source.

An article by Alan MacRobert from Sky and Telescope Magazine about the star Algol (Beta Persei) was the first eclipsing variable star ever discovered.

An article by John Isles from Sky and Telescope Magazine.

Observing variable stars.

A critical review of the Cepheid distance scale, from its inception, to the Hipparcos mission and beyond.