| #491 | OCLC systems & services. -- Westport : Meckler, 1993-. -- ISSN 1065-075X |
| #492 | Ohio libraries. -- Columbus : Ohio Libraries, 1988-2005. -- ISSN 1046-4336 |
| #493 | On-line review : The international journal of online (and videotex) information systems. -- Oxford : Learned Information Europe, 1977-1992. -- ISSN 0309-314X |
| #494 | Online : the magazine of online information systems. -- Wilton : Online, 1977-2012. -- ISSN 0146-5422 |
| #495 | Online & CD ROM review : The International Journal of Online & Optical Information Systems. -- Oxford : Learned Information (Europe) Ltd., 1993-1999. -- ISSN 1353-2642 |
| #496 | Online information review. -- Bradford : MCB University Press., 2000-. -- ISSN 1468-4527 |
| #497 | Online searcher : information discovery, technology, strategies. -- Medford : Information Today, 2013-. -- ISSN 2324-9684 |
| #498 | Open systems today : the newspaper of UNIX and interoperable computing. -- Manhasset : CMP Publications, 1992-1995. -- ISSN 1040-5038 |
| #499 | Országos széchényi Könyvtár évkönyve. -- Budapest : OSZK, 1957-. -- ISSN 0524-8868 |
| #500 | Pakistan journal of library and information science. -- Lahore : Department of Library and Information Science, 2000-. -- ISSN 1680-4465 |