| #251 | Commentarii mathematici Helvetici. -- Basel : Birkhäuser, 1929-. -- ISSN 0010-2571 print. -- ISSN 1420-8946 online |
| #252 | Commentarii Mathematici Universitatis Sancti Pauli. -- Tokyo : Institute of Mathematics, 1952-. -- ISSN 0010-258X |
| #253 | Commentationes Mathematicae Universitatis Carolinae. -- Prague : Charles University, 1960-. -- ISSN 0010-2628 print. -- ISSN 1213-7243 online |
| #254 | Commentationes physico-mathematicae. -- Helsinki : Society Scientiarum Fennica, 1922-1994. -- ISSN 0069-6609 |
| #255 | Communications in algebra. -- New York : Marcel Dekker, 1974-. -- ISSN 0092-7872 print. -- ISSN 1532-4125 online |
| #256 | Communications in analysis and geometry. -- Hong Kong : International Press, 1993-. -- ISSN 1019-8385 print. -- ISSN 1944-9992 online |
| #257 | Communications in applied mathematics and computational science. -- Berkeley, CA : Mathematical Sciences Publishers, 2006-. -- ISSN 1559-3940 print. -- ISSN 2157-5452 online |
| #258 | Communications in applied numerical methods. -- Chichester : Wiley, 1985-1992. -- ISSN 0748-8025 print. -- ISSN 1555-2047 online |
| #259 | Communications in Mathematical Physics. -- Heidelberg : Springer, 1965-. -- ISSN 0010-3616 |
| #260 | Communications in Mathematics. -- Ostrava : The University of Ostrava, 2010-. -- ISSN 1804-1388 |