Reading Recommendations for Couple who are interested in cuckolding

I have a couple who are interested in the cuckolding world, I'm currently speaking to the Mr, but Mrs has expressed that she'd like to read and research more into it.

Now I have an Amazon recommendation about hotwifing, but don't know of any in cuckolding, so send me your recommendations, either online, Reddit, websites etc or books..

Thanks
 
My wife would go back and forth all the time. She would get super into it for a while, doing role play with the big strap on and exchanging Snapchats her hung friend. Then she would suddenly pull back and not be into it as much or at all. I think she still has some underlying concerns about me waiting to share her with her friend and didn’t fully understand it. I found his article online and sent it to her. Gave her a better perspective on reasons why guys typically do it and that it’s much more common than she realized. It seemed to help her since there was a noticeable difference since then.