There are 1,545 titles that begin with the letter O
- Open Engineering (EISSN: 2391-5439)
- Open file report (ISSN: 0149-984X)
- Open Forum Infectious Diseases (ISSN: 2328-8957)
- Open Gender Journal (EISSN: 2512-5192)
- Open Geomechanics (EISSN: 2644-9676)
- Open Geosciences (EISSN: 2391-5447)
- Open Geospatial Data, Software and Standards (EISSN: 2363-7501)
- Open Health (ISSN: 2544-9826)
- Open Health Data (EISSN: 2054-7102)
- The Open Health Services and Policy Journal (ISSN: 1874-9240)
- Open Heart (ISSN: 2398-595X,EISSN: 2053-3624)
- Open Information Science (EISSN: 2451-1781)
- Open Innovations Association (FRUCT), Conference of (ISSN: 2305-7254)
- The Open inorganic chemistry journal (ISSN: 1874-0987)
- Open Journal for Legal Studies (EISSN: 2620-0619)
- Open Journal of Astrophysics (EISSN: 2565-6120)
- Open Journal of Bioresources (EISSN: 2056-5542)
- Open Journal of Cardiovascular Surgery (ISSN: 1179-0652)
- Open Journal of Humanities (EISSN: 2612-6966)
- Open journal of implant dentistry (ISSN: 2226-4507)
- Open Journal of Mathematical Analysis (ISSN: 2616-8103,EISSN: 2616-8111)
- Open Journal of Mathematical Sciences (ISSN: 2616-4906,EISSN: 2523-0212)
- Open Journal of Occupational Therapy (ISSN: 2168-6408)
- Open Journal of Psychiatry and Allied Sciences (ISSN: 2394-2053,EISSN: 2394-2061)
- Open learning (ISSN: 0268-0513,EISSN: 1469-9958)
- Open Life Sciences (EISSN: 2391-5412)
- Open Linguistics (ISSN: 2300-9969)
- The Open Macromolecules Journal (ISSN: 1874-3439)
- Open Management (EISSN: 2451-344X)
- Open Material Sciences (EISSN: 2544-7300)
- The Open Materials Science Journal (ISSN: 1874-088X)
- Open Mathematics (EISSN: 2391-5455)
- The Open Medical Informatics Journal (EISSN: 1874-4311)
- Open Medicinal Chemistry Journal (EISSN: 1874-1045)
- Open Medicine (EISSN: 2391-5463)
- Open Medicine (ISSN: 1911-2092)
- The Open Microbiology Journal (EISSN: 1874-2858)
- Open Military Studies (EISSN: 2545-3254)
- Open Mind: Discoveries in Cognitive Science (EISSN: 2470-2986)
- The Open Mineralogy Journal (ISSN: 1874-4567)
- Open Nanoscience Journal (ISSN: 1874-1401)
- Open Network Biology (ISSN: 2046-7826)
- The Open neuroimaging journal (EISSN: 1874-4400)
- The Open Neurology Journal (EISSN: 1874-205X)
- The open nursing journal (EISSN: 1874-4346)
- Open Ophthalmology Journal (ISSN: 1874-3641)
- The Open Organic Chemistry Journal (ISSN: 1874-0952)
- The Open Orthopaedics Journal (EISSN: 1874-3250)
- Open Philosophy (EISSN: 2543-8875)
- The Open physical chemistry journal (ISSN: 1874-0677)
- Open Physics (EISSN: 2391-5471)
- Open Political Science (EISSN: 2543-8042)
- Open praxis (ISSN: 1369-9997,EISSN: 2304-070X)
- Open Psychology (EISSN: 2543-8883)
- Open Quaternary (EISSN: 2055-298X)
- Open Ranks
- Open Research Computation (ISSN: 2042-5767)
- Open Research Europe (EISSN: 2732-5121)
- Open Respiratory Archives (EISSN: 2659-6636)
- Open Respiratory Medicine Journal (EISSN: 1874-3064)
- Open review of educational research (ISSN: 2326-5507)
- Open Rheumatology Journal (EISSN: 1874-3129)
- Open rivers (ISSN: 2471-190X)
- OPEN ROAD (ISSN: 0048-1947)
- Open Screens (ISSN: 2516-2888)
- Open Shelf (ISSN: 2368-1837)
- Open Sights
- Open Solutions Inc. MarketLine Company Profile
- The Open Source Business Resource (ISSN: 1913-6102)
- Open Source FOR You
- Open Source Jahrbuch
- The Open spectroscopy journal (ISSN: 1874-3838)
- Open Statistics (EISSN: 2657-3601)
- Open Text Corporation MarketLine Company Profile
- Open Theology (ISSN: 2300-6579)
- The Open Thermodynamics Journal (ISSN: 1874-396X)
- The Open Toxicology Journal (ISSN: 1874-3404)
- Open Veterinary Journal (ISSN: 2226-4485,EISSN: 2218-6050)
- Open Veterinary Science (ISSN: 2544-8951)
- Open Virology Journal (EISSN: 1874-3579)
- Openings (ISSN: 2326-0157)
- OpenNano (EISSN: 2352-9520)
- OpenPhysio (EISSN: 2631-8369)
- OpenSource For You
- Opera Canada (ISSN: 0030-3577)
- The Opera journal (ISSN: 0030-3585)
- Opera News (ISSN: 0030-3607,EISSN: 1938-1506)
- The Opera Quarterly (ISSN: 0736-0053,EISSN: 1476-2870)
- Opera Slavica (ISSN: 1211-7676,EISSN: 2336-4459)
- Opera Software ASA MarketLine Company Profile
- The operating theatre journal (ISSN: 1747-728X)
- Operation County fair Newsletter
- Operational Research (ISSN: 1109-2858,EISSN: 1866-1505)
- Operational Research in Engineering Sciences: Theory and Applications (ORESTA) (ISSN: 2620-1607,EISSN: 2620-1747)
- Operational Research Quarterly (1950-1952) (ISSN: 1473-284X,EISSN: 2397-5350)
- Operational Research Quarterly (1970-1977) (ISSN: 0030-3623,EISSN: 2397-5334)
- Operational Risk & Regulation (ISSN: 2045-0672)
- Operations & Fulfillment (ISSN: 1069-6083)
- Operations & Fulfillment
- Operations Management (ISSN: 1529-5648)