| Marcel Martin | PRIMO - "Elliptic Curve Primality Proving" software |
| Andreas Enge | CM - "Elliptic Curve Primality Proving" software |
| N. J. A. Sloane | OEIS - The On-Line Encyclopedia of Integer Sequences |
| Thomas J. Engelsma | Permissible patterns of prime k-tuplets |
| Robin Whitty | Theorem of the Day |
| Dr. Minh. L. Perez Press | Smarandache Primes |
| Henri Lifchitz & Renaud Lifchitz | PRP -records |
| Patrick De Geest | World!Of Numbers |
| Riecoin | Constellation Explorer |
| Makoto Kamada | Factorization of Repunits |
| Markus Tervooren | Data Base of Factors (factordb.com) |
| Matthew C. Anderson, hosted by Norman Luhn | Prime Constellations Page Blog of Matthew C. Anderson on mersenneforum.org |
| GIMPS | Great Internet Mersenne Prime Search |
| Dario Alpern | Integer factorization calculator |
| Henri Lifchitz | BiTwin records |