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| NORRIS (Andrew) | Falkland Islands: the ‘Travis’ franks & covers [1977] | N/A |
| NORRIS (JA) | A Photographic & Cartographic Compilation of London District Post Offices [2009] | N/A |
| NORSK FILATELISTFORBUND | Handbok over Norges Frimerker 1855-1955, Vol. 1 – 1855-1888; Vol. 2 – 1886-1955 | Scandinavia |
| NORTH (B) | The Post, a Universal link between men [1974] | N/A |
| NORTH (Stephen J) | German Mail boats from Europe to East Africa 1890 – 1905 [2002] | Maritime |
| NORTH (Stephen J) | The British India Steam Navigation Company’s packets to East Africa: 1890-1905 [1990] | Maritime |
| NORWAY (Arthur H) | History of the Post-office packet service between the years 1793-1815 [1895] | Maritime |
| NORWAY: POST OFFICE | A brief summary of the Norwegian postal history [1977] | Scandinavia |
| NUTHALL (DA) | The surcharging of Rhodesia’s mail | N/A |
| O'CONNOR (T.P.) | Colonial American Postal History 1675-1783 [2018] | N/A |
| O'NEILL (CP & SP) | Armagh Post Office, Its History and Post Marks nd | N/A |
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| OGILBY (John) | Britannia, Volume the first: or, an illustration of the Kingdom of England & Dominion of Wales. [1675].. | N/A |
| OHRT (Paul) | Die poststempel von Oldenburg…[1911] | Germany |
| OJASTE (Elmar) | Eesti / Estonia philately & postal history handbook-catalogue / Estland philatelie und postgeschichte | Baltic States |
| OLAMO (Juhani) | Suomen postileimojen kasikirja: II osa [the ‘Two-ring’ postmarks of Finland 1873-1893 [1977] | Scandinavia |
| OLIER (F) | Hopitaux Militaires dans la Guerre 1914-1918 Vol: 1 France nord-ouest [2008]; Vol 2 Paris France Centre [2010]; Vol 3 France sud-ouest [nd] | France, WW1 |
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| OMAN POST | The postal history of Oman 1856-1985 [1985] | N/A |
| ORCHARD (A E) | The post offices of Tasmania: openings and closures 1812 to 1991 [1991] | N/A |
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| OSBORN (Geoffrey) | Naval officers’ letters: a study of letters sent to and from British Royal Navy officers serving abroad in the Victorian era [1995] | Maritime |
| OSBORN (Geoffrey) | Gibraltar: the postal,history and postage stamps, Vol 1 to 1885 [1995] | N/A |
| OSBORN (Geoffrey) | The Royal Mail Steam Packets to Bermuda & the Bahamas 1842-1859 | Maritime |
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| OTH (Jean) | Le Controle des communications et les directives postales 1944-1945 [1987] | WW2 |
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| OXLEY (Geoff F) | The postal history of Ceylon 1795-1857 [2001] | N/A |
| OXLEY (Geoff F) | The English Provincial Local Posts 1765-1840 [1973] with supplement: A rarity guide | Great Britain, Local |
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| OXLEY (HM) | A Postal History of Durham City [1980] | N/A |
| P&O POCKET BOOK | Fourth issue [1926] | Maritime |
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| PADGET (P I) | The Postal Markings of China [1981] | N/A |
| PAEZ T (Rodrigo) | Ecuador postal history and a listing of prephilatelic postmarks | N/A |
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| PAI (G B) | A collection of the catalogue, statutes and notices relating to Indian Post Office till the end of 19th century [1997] | N/A |
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| PANNETIER (P-L), | Les correspondances des colonies francaises avec timbres des emissions generales: La Guadeloupe | Colonies, France |
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| PARMENTER (John) | Low number suburban ovals: cancellations of the London district post and subsequent suburban districts [2000] | N/A |
| PARMENTER (John) | London Late Fee and Too Late mail 1840-1930 | N/A |
| PARMENTER (John) | GB used abroad: cancellations & postal markings [1993]; Revised Edition [2016] | N/A |
| PARMENTER (John) | The barred numeral cancellations, 6 vol Vol. 1 – Wales; Vol. 2 – B to D; Vol. 3 – E to K; Vol.4 – L to N; Vol. 5 – O to S; Vol. 6 – W to Y [1984-88] | Great Britain |
| PARSBRO (L) | The First Stamp of North Borneo – the 1883 2 cents brown [2004] | N/A |
