University of California, San Diego: Edward Bender and S. Williamson's "Sets, Equivalence and Order: Sets and Functions"

Read "Set Properties and Proofs" on pages SF-2 - SF-6.

Click https://s3.amazonaws.com/saylordotorg-resources/wwwresources/site/wp-content/uploads/2011/09/CS202-Sets-and-Functions-Edward-Benderand-S.-Gill-Williamson.pdf link to open resource.