I’m sure lots of books will be recommended but, after smoking for 15 years and trying tons of times to quit, I finally quit after reading Allen Carrs Easy Way to Stop Smoking.
I read about Allen Carrs book on Reddit in the comments of a few posts. People kept saying how great it was and called it the ‘quit smoking Bible’. It wasn’t that expensive so I picked it up and it really did work for me 🤷♀️
Good luck to your friend
Thanks friend