Mint Errors To Die For
https://portsmouthcoinshop.com/product/pre-order-mint-errors-to-die-for-by-joseph-conin/
Strike It Rich
https://amzn.to/3jp4W1r
CONECA
https://conecaonline.org/
Error Reference
Fact Coins and Notes
Coin Searchers Are Doing It Wrong! You Have To Do This First!