| Nennius | Historia Brittonum | Eighth century historian with a love of romance and invention. His work cannot be dismissed entirely because he had access to old sources. |
| Nicholaisen W F H, | Scottish place-names | London 1978 |
| Orosius P, | Historiae aduersum Paganos, Panegyrici Latini | Written around 410, his seven books are the first world history by a Christian. Reliable for 378 to 417 he was used by Gidas and Bede. |
| Patricius | Confessio | |
| Plinius C, Secundus | Historia Naturalis | His encyclopedia, published in 47 C.E. has a chapter on the western Mediterranean. Used by Tacitus. |
| Price G, | The languages of Britain | London 1984 |
| Ptolemaeus C, | Geography | Alexandrian scholar mid-second century CE uses earlier materials including lost work of Marinus of Tyre. |
| Reaney P H, | The origin of English place-names | London 1960 |
| Richmond I A | Roman Britain | Penguin 1955 |
| Rivet A L F Jackson K, | The British section of the Antonine Itinerary | Britannia I 1970 |
| Rivet A L F Smith C, | The place-names of Roman Britain | London 1979 |
| Ross A, | Pagan Celtic Britain | London 1974 |
| Roucoux O, | The Roman Watling Street | Dunstable Museum Trust 1984 |
| Tacitus P C, | Agricola, Annales | The Agricola was published in 98 CE |
| Todd M, | Roman Britain 500 BC-AD 400 | Fontana 1985 |
| Wacher J, | The coming of Rome | Paladin 1981 |
| Wainwright F T, | Archaeology and Place-names and History | Routledge 1962 |
| Wainwright F T, | Scandinavian England | Chichester 1975 |
| Watson W J, | The Celtic Place-Names of Scotland | Edinburg 2004 |
| Xiphilinos | Epitome Dionis Nikaiensis | |