Bing found the following results
Yahoo! JAPAN
Yahoo
GitHub - bbuhrow/yafu: Automated integer factorization
Yahoo
yafu download | SourceForge.net
math - Number factorisation using Yafu - Stack Overflow
Beginners' Guide To Factoring
Downloading File /1.34/yafu-1.34.zip - yafu - OSDN
Unofficial mirror of yafu. Go to - GitHub
YAFU for factorizing extremely large numbers - Stack Overflow