1. {1}. http://www.gsm-security.net/ {1}. http://www.gsm-security.net/
2. {2}. http://www.crypto.com/papers/others/a5.ps {2}. http://www.crypto.com/papers/others/a5.ps
3. {3}. http://jya.com/crack-a5.htm {3}. http://jya.com/crack-a5.htm
4. {4}. www.isaac.cs.berkeley.edu/isaac/mobicom.pdf {4}. www.isaac.cs.berkeley.edu/isaac/mobicom.pdf
5. {5}. www.it.kth.se/courses/2G1723/lectures/encryption.pdf {5}. www.it.kth.se/courses/2G1723/lectures/encryption.pdf