The ADA Checklist at this Amazon link is still the current version:
Version 1.4 (the fourth version) is the latest release, published on June 27, 2019. This website is still undergoing updates and will be completed along with other Kris Rivenburgh ADA projects. You can contact me at krisrivenburgh [at] gmail [dot] com.
For more info on the legal situation involving ADA website compliance, read my Medium article: