How to move books from iBooks on my iPhone with iTunes on Mac?
Did you buy them from the iTunes Store? If so, they should sync automatically via iTunes into iBooks on your Mac. If you got them externally to iTunes, then you will have to separately move them to your Mac first before using iTunes on your Mac. Can you mail them to yourself and import them into iBooks on your Mac? It does matter which version of iTunes and OSX you are using as the behaviour of iTunes and iBooks has changed between releases, however the fundamental point is that you need to move them independently of iTunes to your Mac first.