I wrote a book on chopmarked coins, published on Amazon in June of this year: https://www.amazon.com/dp/B0C79L8GCT.

Chopmarks always seem to attract a positive response on r/coins and I wish I could share the link directly in the comments of some of these posts, but I don't want to run afoul of the sub's rules. If anyone has any interest in chops, I think it's a very handy reference, with more than 300 images and tons of period details!

Also, come visit us over at r/ChopmarkedCoins!