- Oficina nueva de Arazoza y Soler (Havana) (1)
- Ogilvie (Montreal, Canada) (1)
- Ohio State Commissioners of Public Printing (Columbus) (1)
- Oklahoma Geological Survey (Norman, Oklahoma?) (1)
- Oklahoma News Company (Tulsa, Oklahoma) (1)
- Okuratnaia karta chasti Kamchatki s polozheniem Okhotskago Berega sovsemi Kurilskimi Ostrovami i chastiiuzh IAponii, takozh sieverozapadnoi Ameriki sovsemi Aleutskimi Ostrovami, ili Sieverym Arkhipelagom protiv prezhnikh opisei : vypravlena v Yrkutskie 17 (1)
- Oldsmobile Division, General Motors Corp. (4)
- Oldsmobile Division, General Motors Corporation, 1942 (1)
- Oliver & Boyd (Edinburgh) (1)
- Oliver Ditson & Co (Boston) (2)
- Oliver Ditson & Co. (Boston) (1)
- Oliver Ditson (Boston) (3)
- Oliver Ditson Company (Boston), 1920 (1)
- Oliver Ditson Company (Boston, Massachucetts), 1919 (1)
- Oliver Iron Mining Co., Mining Engineering Dept. ; Duluth, Minnesota (1)
- Ommation Press (Chicago) (1)
- On sale at U.S. Lake Survey Office (Detroit, Mich) (1)
- On sale at U.S. Lake Survey Office (Detroit, Michigan) (1)
- Opus Playhouse (1)
- Orchid Album: Comprising Coloured Figures and Descriptions of New, Rare and Orchidaceous Plants. London: B.S. Williams (London) (2)
