Thanissaro Bhikkhu has written a fairly hefty tome called ‘On The Path’ regarding the Noble Eightfold Path. I am reading it at the moment and it is certainly worth the time and investment for your practice. I offer it here as a service to all and trust that it will serve your practice as it is so doing with mine.
On The Path
I have, as usual, placed it in the eLibrary. It is covered by its own Creative Commons License.