There are 1,585 titles that begin with the letter O
- 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)
- Opera (ISSN: 1657-8651,EISSN: 2346-2159)
- 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 (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)
- Operations Management Education Review (ISSN: 1649-7082,EISSN: 2044-4567)
- Operations Management Research (ISSN: 1936-9735,EISSN: 1936-9743)
- OPERATIONS RESEARCH (ISSN: 0030-364X,EISSN: 1526-5463)
- Operations Research and Decisions (ISSN: 2081-8858)
- Operations Research for Health Care (ISSN: 2211-6923,EISSN: 2211-6931)
- Operations Research Forum (EISSN: 2662-2556)
- OPERATIONS RESEARCH LETTERS (ISSN: 0167-6377,EISSN: 1872-7468)
- OPERATIONS RESEARCH PERSPECTIVES (ISSN: 2214-7160)
- OPERATIVE DENTISTRY (ISSN: 0361-7734,EISSN: 1559-2863)
- OPERATIVE NEUROSURGERY (ISSN: 2332-4252,EISSN: 2332-4260)
- Operative Orthopädie und Traumatologie (ISSN: 0934-6694,EISSN: 1439-0981)
- Operative techniques in cardiac & thoracic surgery (ISSN: 1085-5637,EISSN: 1876-4770)
- Operative techniques in general surgery (ISSN: 1524-153X,EISSN: 1558-383X)
- Operative techniques in neurosurgery (ISSN: 1092-440X,EISSN: 1557-9409)
- Operative techniques in orthopaedics (ISSN: 1048-6666,EISSN: 1558-3848)
- Operative techniques in otolaryngology--head and neck surgery (ISSN: 1043-1810,EISSN: 1557-9395)
- Operative techniques in plastic and reconstructive surgery (ISSN: 1071-0949,EISSN: 1558-0741)
- OPERATIVE TECHNIQUES IN SPORTS MEDICINE (ISSN: 1060-1872,EISSN: 1557-9794)
- Operative techniques in thoracic and cardiovascular surgery (ISSN: 1522-2942,EISSN: 1532-8627)
- Opflow (ISSN: 0149-8029,EISSN: 1551-8701)
- OPHTHALMIC AND PHYSIOLOGICAL OPTICS (ISSN: 0275-5408,EISSN: 1475-1313)
- OPHTHALMIC EPIDEMIOLOGY (ISSN: 0928-6586,EISSN: 1744-5086)
- OPHTHALMIC GENETICS (ISSN: 1381-6810,EISSN: 1744-5094)
- Ophthalmic paediatrics and genetics (ISSN: 0167-6784)
- OPHTHALMIC PLASTIC AND RECONSTRUCTIVE SURGERY (ISSN: 0740-9303,EISSN: 1537-2677)
- Der Ophthalmologe (ISSN: 0941-293X,EISSN: 1433-0423)
- OPHTHALMOLOGY (ISSN: 0161-6420,EISSN: 1549-4713)
- Ophthalmology and Eye Diseases (EISSN: 1179-1721)
- OPHTHALMOLOGY AND THERAPY (ISSN: 2193-8245,EISSN: 2193-6528)
- Ophthalmology Journal (ISSN: 2450-7873,EISSN: 2450-9930)
- Ophthalmology Science (ISSN: 2666-9145)
- Ophthalmology Times (ISSN: 0193-032X,EISSN: 2150-7333)
- Ophthalmology Update (ISSN: 1993-2863)
- Opinion Piece in Macedonian Press
- L'opinion publique (ISSN: 0711-7477)
- L'opinion publique : journal illustré
- Opinião Pública (ISSN: 0104-6276,EISSN: 1807-0191)
- La Opinión (ISSN: 0276-590X)
- Opinión Jurídica (ISSN: 1692-2530,EISSN: 2248-4078)
- Oplink Communications, Inc. MarketLine Company Profile
- Opolskie Studia Administracyjno-Prawne (ISSN: 1731-8297,EISSN: 2658-1922)
- Oppdragsrapport. A - Norges vassdrags- og energidirektorat (ISSN: 1503-0318)
- Oppenheimer Holdings Inc. MarketLine Company Profile
- Opportunistic pathogens (ISSN: 1386-2618,EISSN: 1878-3694)
- Opportunities for Research in Renaissance Drama (ISSN: 2378-4016,EISSN: 2380-1166)
- Opportunities for Research in Renaissance Drama (Exclusive of Shakespeare) (ISSN: 2378-3990,EISSN: 2380-1182)
- The Oppressed
- OPSEARCH (ISSN: 0030-3887,EISSN: 0975-0320)
- OPSI (ISSN: 1693-2102,EISSN: 2686-2352)
- OPTICA (ISSN: 2334-2536)
- OPTICA APPLICATA (ISSN: 0078-5466,EISSN: 1899-7015)
- Optical and Quantum Electronics (ISSN: 0306-8919,EISSN: 1572-817X)
- Optical Cable Corporation MarketLine Company Profile
- Optical Data Processing and Storage (EISSN: 2084-8862)
- OPTICAL ENGINEERING (ISSN: 0091-3286,EISSN: 1560-2303)
- Optical Fiber Communication (OFC)Conference
- OPTICAL FIBER TECHNOLOGY (ISSN: 1068-5200,EISSN: 1095-9912)
- Optical Interconnects Conference, IEEE (ISSN: 2376-8665)
- OPTICAL MATERIALS (ISSN: 0925-3467,EISSN: 1873-1252)
- OPTICAL MATERIALS EXPRESS (ISSN: 2159-3930)
- Optical Materials: X (EISSN: 2590-1478)
- Optical Memory & Neural Networks (ISSN: 1060-992X,EISSN: 1934-7898)
- Optical Memory News (ISSN: 0741-5869)
- Optical MEMS, IEEE/LEOS International Conference on (ISSN: 2160-5033,EISSN: 2160-5041)
- Optical Nanoscopy (ISSN: 2192-2853)
- Optical Review (ISSN: 1340-6000,EISSN: 1349-9432)
- OPTICAL SWITCHING AND NETWORKING (ISSN: 1573-4277,EISSN: 1872-9770)
- Optician (ISSN: 0030-3968,EISSN: 2632-0010)
- Opticon1826 (ISSN: 2049-8128)
- Optics (EISSN: 2673-3269)
- OPTICS AND LASER TECHNOLOGY (ISSN: 0030-3992,EISSN: 1879-2545)
- OPTICS AND LASERS IN ENGINEERING (ISSN: 0143-8166,EISSN: 1873-0302)