| #261 | Packet : Cisco systems users magazine. -- San Jose : Cisco Systems |
| #262 | Periodica polytechnica, Electrical engineering. -- Budapest : Technical University, 1957-. -- ISSN 0324-6000 |
| #263 | Portable design : The authority for mobile technologies and products. -- Tulsa : PennWell, 1995-. -- ISSN 1086-1300 |
| #264 | Poštovní věstník. -- Praha : Český telekomunikační úřad, 1993-. -- ISSN 1211-2704 |
| #265 | Prace Przemyslowego Instytutu Telekomunikacji. -- Warszawa : Przemyslowy instytut telekomunikacji, 1951-. -- ISSN 0032-6283 |
| #266 | Practical wireless. -- Poole : IPC Magazines, 1950-. -- ISSN 0141-0857 |
| #267 | Praktická elektronika - Amatérské radio. -- Praha : Amaro s.r.o., 2011-. -- ISSN 1804-7173 |
| #268 | Pro sound news. -- London : Pro Sound News Publications, Spotlight Publications Limited, 1986-. -- ISSN 0269-4735 |
| #269 | Proceedings of the Institute of Radio Engineers. -- New York : Institute of Radio Engineers, 1913-1938. -- ISSN 0731-5996 print. -- ISSN 2162-6626 online |
| #270 | Proceedings of the Institution of Electrical Engineers, Part B, Electronic and communication engineering, including radio engineering. -- London : Institution of Electrical Engineers, 1959-1962. -- ISSN 0369-8890 print. -- ISSN 2054-0418 online |