| Operations Research for Health Care | OPERATIONS RESEARCH FOR HEALTH CARE | 2211-6923 |
| Operations Research Letters | OPER RES LETT | 0167-6377 |
| Operations Research Perpsectives | OPERATIONS RESEARCH PERPSECTIVES | 2214-7160 |
| Operative Dentistry | OPER DENT | 0361-7734 |
| Operative Neurosurgery | OPERATIVE NEUROSURGERY | 2332-4252 |
| Operative Orthopadie und Traumatologie | OPER ORTHOP TRAUMATO | 0934-6694 |
| Operative Techniques in Orthopaedics | OPERATIVE TECHNIQUES IN ORTHOPAEDICS | 1048-6666 |
| Operative Techniques in Otolaryngology - Head and Neck Surgery | OPERATIVE TECHNIQUES IN OTOLARYNGOLOGY - HEAD AND NECK SURGERY | 1043-1810 |
| Operative Techniques in Sports Medicine | OPER TECHN SPORT MED | 1060-1872 |
| Operative Techniques in Thoracic and Cardiovascular Surgery | OPERATIVE TECHNIQUES IN THORACIC AND CARDIOVASCULAR SURGERY | 1522-2942 |
| Operators and Matrices | OPER MATRICES | 1846-3886 |
| Opere et Studio Pro Oeconomia | | |
| Ophelia | | |
| Ophthalmic and Physiological Optics | OPHTHAL PHYSL OPT | 0275-5408 |
| Ophthalmic Epidemiology | OPHTHAL EPIDEMIOL | 0928-6586 |
| Ophthalmic Genetics | OPHTHALMIC GENET | 1381-6810 |
| Ophthalmic Plastic and Reconstructive Surgery | OPHTHAL PLAST RECONS | 0740-9303 |
| Ophthalmic Research | OPHTHALMIC RES | 0030-3747 |
| Ophthalmic Surgery Lasers & Imaging | OPHTHAL SURG LAS IM | 1542-8877 |
| Ophthalmic Surgery Lasers & Imaging Retina | OPHTHALMIC SURGERY LASERS & IMAGING RETINA | 2325-8160 |
| Der Ophthalmologe | OPHTHALMOLOGE | 0941-293X |
| Ophthalmologica | OPHTHALMOLOGICA | 0030-3755 |
| Ophthalmology | OPHTHALMOLOGY | 0161-6420 |
| Ophthalmology and Therapy | OPHTHALMOLOGY AND THERAPY | 2193-8245 |
| Ophthalmology in China | OPHTHALMOLOGY IN CHINA | 1004-4469 |
| Ophthalmology Journal | OPHTHALMOLOGY JOURNAL | 2450-7873 |
| Ophthalmology Retina | OPHTHALMOLOGY RETINA | 2468-7219 |
| OphthaTherapy. Terapie w Okulistyce | OPHTHATHERAPY. TERAPIE W OKULISTYCE | 2353-7175 |
| Opiniao Publica | OPINIAO PUBLICA | 0104-6276 |
| Opinie Edukacyjne Polskiej Akademii Umiejętności. Prace Komisji Pau Do Oceny Podręczników Szkolnych | | 1733-5175 |
| Opir Materialiv i Teoria Sporud-Strength of Materials and Theory of Structures | OPIR MATERIALIV I TEORIA SPORUD-STRENGTH OF MATERIALS AND THEORY OF STRUCTURES | 0132-1471 |
| Opm - Ogólnopolski Przegląd Medyczny | | 1641-7348 |
| Opolskie Studia Administracyjno-Prawne | | 1731-8297 |
| Opsearch | OPSEARCH | 0030-3887 |
| Optica | OPTICA | 2334-2536 |
| Optica Applicata | OPT APPL | 0078-5466 |
| Optica Pura y Aplicada | OPTICA PURA Y APLICADA | 0030-3917 |
| Optical and Quantum Electronics | OPT QUANT ELECTRON | 0306-8919 |
| Optical Engineering | OPT ENG | 0091-3286 |
| Optical Fiber Technology | OPT FIBER TECHNOL | 1068-5200 |
| Optical Materials | OPT MATER | 0925-3467 |
| Optical Materials Express | OPT MATER EXPRESS | 2159-3930 |
| Optical Materials: X | OPTICAL MATERIALS: X | 2590-1478 |
| Optical Memory and Neural Networks (Information Optics) | OPTICAL MEMORY AND NEURAL NETWORKS (INFORMATION OPTICS) | 1060-992X |
| Optical Review | OPT REV | 1340-6000 |
| Optical Switching and Networking | OPT SWITCH NETW | 1573-4277 |
| Optics and Laser Technology | OPT LASER TECHNOL | 0030-3992 |
| Optics and Lasers in Engineering | OPT LASER ENG | 0143-8166 |
| Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | OPT SPECTROSC+ | 0030-400X |
| Optics Communications | OPT COMMUN | 0030-4018 |
