Shirley Glass in my opinion is/was the most knowledgeable author on infidelity.
She unfortunately passed away before writing a second book... she spent so much time researching the first one to make it as good as it is...
Harley has his own website and is a published Author
Penny Tuppy has an eBook on confrontation and protection phases of her appraoch, again online.
My main point, and still is my point, is that the DR book is mostly for rebuilding a marriage, it does not offer effective strategies for combating affairs... particularly the overt kind where the spouse refuses to end the affair.
Even MWD offers advice for CATCHING someone having an affair.. bug their PC with spyware.. but AFTER that confrontation and proof of an affair, she offers very little advice on how to deal with the fallout.. in some cases on this forum the affair goes on for over a year after that... how does a LBS survive that year? how do they fight back?
Penny Tuppy is largely the resource I draw on, but she bases her position on Harley and Glass who are strong advocates of infidelity being handled like any other addiction - intervention, confontation, protection, etc
MWD herself has an endorsement on the cover of Glass' book Not Just Friends.. so you know its DB-Friendly....