- On Land and Sea at the DardanellesAuthor: T. C. (Thomas Charles) BridgesLanguage: English
- On the Banks of the AmazonAuthor: William Henry Giles Kingston, William H. C. GroomeLanguage: English
- On The BlockadeAuthor: Oliver Optic, L. J. (Lewis Jesse) BridgmanLanguage: English
- On the Edge of the Arctic; Or, An Aeroplane in SnowlandAuthor: H. L. (Harry Lincoln) Sayler, Hall, N. P. [Illustrator]Language: English
- On the Firing LineAuthor: Anna Chapin Ray, Fuller, Hamilton BrockLanguage: English
- On the Irrawaddy: A Story of the First Burmese WarAuthor: G. A. (George Alfred) Henty, William Heysham OverendLanguage: English
- On the Pampas; Or, The Young SettlersAuthor: G. A. (George Alfred) HentyLanguage: English
- On the Spanish Main; Or, Some English forays on the Isthmus of DarienAuthor: John MasefieldLanguage: English
- On the Trail of Pontiac; Or, The Pioneer Boys of the OhioAuthor: Edward StratemeyerLanguage: English
- On the Trail of the Space PiratesAuthor: Rockwell, Carey, Willy Ley, Glanzman, Louis [Illustrator]Language: English
- Once Upon A TimeAuthor: Richard Harding DavisLanguage: English
- One of the 28th: A Tale of WaterlooAuthor: G. A. (George Alfred) HentyLanguage: English
- One Wonderful Night: A Romance of New YorkAuthor: Louis TracyLanguage: English
- Oonomoo the HuronAuthor: Edward Sylvester EllisLanguage: English
- Op de jacht in Mozambique: De Aarde en haar Volken, 1909Author: Vasse, GuillaumeLanguage: Dutch
- Op de olifantenjacht in Oeganda: De Aarde en haar Volken, 1910Author: Langsdorff, Baron deLanguage: Dutch
- Orange and Green: A Tale of the Boyne and LimerickAuthor: G. A. (George Alfred) HentyLanguage: English
- Orlando FuriosoAuthor: Lodovico Ariosto, William Stewart RoseLanguage: English
- Our Boys: Entertaining Stories by Popular AuthorsAuthor: VariousLanguage: English
- Our Pirate Hoard: 1891Author: Thomas A. (Thomas Allibone) JanvierLanguage: English
- Our Soldier BoyAuthor: George Manville Fenn, Venner, Victor [Illustrator]Language: English
- Out of the Fog: A Story of the SeaAuthor: Charles K. (Charles Kellogg) OberLanguage: English
- Out of the PrimitiveAuthor: Robert Ames BennetLanguage: English
- Out of Time's AbyssAuthor: Edgar Rice BurroughsLanguage: English
- Out with Gun and Camera; or, The Boy Hunters in the MountainsAuthor: Edward StratemeyerLanguage: English
- Outward Bound Or, Young America Afloat: A Story of Travel and AdventureAuthor: Oliver OpticLanguage: English
- Over the PassAuthor: Frederick PalmerLanguage: English
- Over the Rocky Mountains to AlaskaAuthor: Charles Warren StoddardLanguage: English
- Over the Rocky Mountains: Wandering Will in the Land of the RedskinAuthor: R. M. (Robert Michael) BallantyneLanguage: English
- Overdue: The Story of a Missing ShipAuthor: Harry Collingwood, W. Herbert (William Herbert) HollowayLanguage: English
- Overland Red: A Romance of the Moonstone Cañon TrailAuthor: Henry Herbert Knibbs, Anton Otto FischerLanguage: English
- Overland: A NovelAuthor: John William De ForestLanguage: English
- Owen Clancy's Happy Trail; Or, The Motor Wizard in CaliforniaAuthor: Burt L. StandishLanguage: English
- Owen Hartley; or, Ups and Downs: A Tale of Land and SeaAuthor: William Henry Giles KingstonLanguage: English
- Paddy FinnAuthor: William Henry Giles Kingston, Archibald WebbLanguage: English
- PardnersAuthor: Rex BeachLanguage: English
- Parnassus on WheelsAuthor: Christopher MorleyLanguage: English
- Parrot & Co.Author: Harold MacGrath, J. André CastaigneLanguage: English
- Partners of ChanceAuthor: Henry Herbert KnibbsLanguage: English
- Pathfinder; or, The Missing TenderfootAuthor: Douglas, Alan, CaptainLanguage: English
- Pathfinders of the West: Being the Thrilling Story of the Adventures of the Men Who: Discovered the Great Northwest: Radisson, La Vérendrye,: Lewis and ClarkAuthor: Agnes C. LautLanguage: English
- Paul Clifford — Volume 03Author: Lytton, Edward Bulwer Lytton, BaronLanguage: English
- Paul Clifford — Volume 05Author: Lytton, Edward Bulwer Lytton, BaronLanguage: English
- Paul Gerrard, the Cabin BoyAuthor: William Henry Giles KingstonLanguage: English
- Paul Prescott's ChargeAuthor: Alger, Horatio, Jr.Language: English
- Paul the CourageousAuthor: Mabel Quiller-CouchLanguage: English
- Peace ManoeuvresAuthor: Richard Harding DavisLanguage: English
- Peaux-rouges et Peaux-blanchesAuthor: H. Emile (Henri Emile) ChevalierLanguage: French
- Peck's Bad Boy with the CowboysAuthor: George W. (George Wilbur) PeckLanguage: English
- Pee-wee Harris AdriftAuthor: Percy Keese Fitzhugh, Harold S. BarbourLanguage: English
- Pee-wee Harris on the TrailAuthor: Percy Keese Fitzhugh, Harold S. BarbourLanguage: English
- PellucidarAuthor: Edgar Rice BurroughsLanguage: English
- Per auto door den Kaukasus naar Perzië: De Aarde en haar Volken, 1907Author: Claude AnetLanguage: Dutch
- Percival KeeneAuthor: Frederick MarryatLanguage: English
- Peregrine's ProgressAuthor: Jeffery FarnolLanguage: English
- Perils and Captivity: Comprising The sufferings of the Picard family after the shipwreck of the Medusa, in the year 1816; Narrative of the captivity of M. de Brisson, in the year 1785; Voyage of Madame Godin along the river of the Amazons, in the year 1770.Author: Charlotte-Adelaïde Dard, Pierre-Raymond de Brisson, Jean Godin des Odonais, Maxwell, Patrick [Translator]Language: English
- Peter Biddulph: The Story of an Australian SettlerAuthor: William Henry Giles KingstonLanguage: English
- Peter PanAuthor: J. M. (James Matthew) BarrieLanguage: English
- Peter Parley's Tales About America and AustraliaAuthor: Samuel G. (Samuel Griswold) Goodrich, T. Wilson, Samuel WilliamsLanguage: English
- Peter SimpleAuthor: Frederick MarryatLanguage: English