1. Most common iPhone passcodes;Amitay,2011
2. Can we fix the security economics of federated authentication?;Anderson,2011
3. Apple Inc. Licensed application end user license agreement, http://www.apple.com/legal/itunes/appstore/dev/stdeula/.
4. Generating and remembering passwords;Brown;Applied Cognitive Psychology,2004
5. Electronic authentication guideline;Burr,2006