Y Llyfr Enwau - Enwau'r Wlad (A check-list of Welsh place-names) by D. Geraint Lewis

This comprehensive reference book, alphabetically lists Welsh place-names with English translations, place-name locations pre-1974 and after the 1996 county changes,  with OS grid references.   An useful volume to have for learning the meanings of different place-names and what the names refer to - parishes, mountains, rivers, monuments, farms etc, and also how to spell the names of places correctly.   The volume also includes maps showing the main rivers, mountains and the county boundaries.