Chopmarked Collectors club
If you are looking to join a new club this might be the one for you. I am a member but I don't collect chopmarked coins simply enjoy reading their journals. The annual fee is pretty low so in my opinion well worth it.
Colin Gullberg has written a boom on the subject it is not a easy book to locate but worth the money if you can find one. He may still have a copy for sale you would have to reach out to him. That is how I was able to buy my copy but that was about a year ago.
You can contact Colin at the following e-mail address if interested: