There are not as many resources related to star clusters and variable stars as there are resources covering topics from previous lessons, but here are a few:
Have another website or printed piece on this topic that you have found useful? Share it in our Comment space below!
Links
[1] http://amazing-space.stsci.edu/resources/organizers/starclusters.php.p=Capture+the+cosmos%40%2Ccapture%2C%3EStellar+evolution%40%2Ccapture%2Cstars%2C
[2] http://www.aavso.org/
[3] https://youtu.be/an4rgJ3O21A