| #491 | Prisma : illustrierte Monatsschrift für Natur, Forschung und Technik. -- Švýcarsko : Zürich : Fretz und Wasmuth, 1946-1953. -- ISSN 1422-0105 |
| #492 | Proceedings of the American Institute of Electrical Engineers. -- New York : American Institute of Electrical Engineers, 1905-1919. -- ISSN 0097-2444 print. -- ISSN 2376-7758 online |
| #493 | Proceedings of the Estonian Academy of Sciences. -- Tallinn : Estonian Academy Publishers, 2008-. -- ISSN 1736-6046 print. -- ISSN 1736-7530 online |
| #494 | Proceedings of the Institute of Radio Engineers. -- New York : Institute of Radio Engineers, 1913-1938. -- ISSN 0731-5996 print. -- ISSN 2162-6626 online |
| #495 | Proceedings of the Institution of Civil Engineers. Part 2, Research and theory. -- Velká Británie : London : Thomas Telford, 1972-1991. -- ISSN 0307-8361 |
| #496 | Proceedings of the Institution of Electrical Engineers, Part A, Power engineering. -- London : Institution of Electrical Engineers, 1955-1962. -- ISSN 0369-8882 print. -- ISSN 2054-040X online |
| #497 | Proceedings of the Institution of Electrical Engineers, Part B, Electronic and communication engineering, including radio engineering. -- London : Institution of Electrical Engineers, 1955-1962. -- ISSN 0369-8890 print. -- ISSN 2054-0418 online |
| #498 | Proceedings of the Institution of Electrical Engineers, Part C, Monographs. -- London : Institution of Electrical Engineers, 1955-1962. -- ISSN 0369-8904 print. -- ISSN 2054-0426 online |
| #499 | Proceedings of the National Academy of Sciences of the United States of America. -- Washington : National Academy of Sciences, 1914-. -- ISSN 0027-8424 print. -- ISSN 1091-6490 online |
| #500 | Proceedings of the Physical Society. -- London : Physical Society, 1926-1948. -- ISSN 0959-5309 |