Everything You Need to Know About Keychain in macOS Sierra
MilitaryCAC's How to clear the login section of keychain on your Mac
How to fix the Mac "accountsd wants to use the login keychain" message
How to fix Keychain problems on Mac
Tax Agency: How to import a valid copy of your electronic certificate - Macintosh - Import copy of the certificate...
How to import your passwords to Apple's iCloud Keychain via Safari - The Verge
Firefox Password Manager - Save and Edit Firefox Passwords
Using iCloud Passwords with third-party b… - Apple Community
GitHub - jfitzell/mozilla-keychain: Store your Firefox website usernames and passwords in Apple's Keychain Services, just like Safari and other browsers do on OS X.
Mac SW Certificate - ITS
MilitaryCAC's How to clear the login section of keychain on your Mac