Good at explaining the WCAG (Web Content Accessibility Guidelines)
The government accessibility blog, lots of good stuff here
My site and article on being an accessibility advocate
Testing native apps and mobiles for accessibility
Great all round resource and creators of the WAVE (Web Accessibility Evaluation Tool) I’ve put a link to an article about a million page review they do but look around for lots of good information https://webaim.org/projects/million/update