When we are in Rome we always call into the Anglo American bookshop at via della Vita, not far from the Spanish Steps. They have a good selection of maps and guidebooks in English.
This time we picked up a copy of Secret Rome published by JonGlez. It’s a good guide book for those making their third or fourth visit to Rome and wanting to check out some sites not listed in most other guides. We found it to be useful, despite the fact that many of the places can only be visited by appointment or have limited opening hours.