I. Forgot and M. Password, How do I reset it? https://www.dropbox.com, 2015.

Y. Security and I. Apple, https://support.apple.com/en-us/HT201303 (2015), [Online; Accessed 15, 2016.

J. Bonneau, E. Bursztein, I. Caron, R. Jackson, and M. Williamson, Secrets, Lies, and Account Recovery, Proceedings of the 24th International Conference on World Wide Web, WWW '15, pp.141-150, 2015.
DOI : 10.1093/comjnl/36.3.227

J. Bonneau and S. Preibusch, The Password Thicket: Technical and Market Failures in Human Authentication on the Web, p.WEIS, 2010.

G. Corder and D. Foreman, Nonparametric Statistics: A Step-by-Step Approach, 2014.

N. Cubrilovic, The Anatomy Of The Twitter Attack, 2009.

A. Dmitrienko, C. Liebchen, C. Rossow, and A. R. Sadeghi, On the (In)Security of Mobile Two-Factor Authentication, Financial Cryptography and Data Security, pp.365-383, 2014.
DOI : 10.1007/978-3-662-45472-5_24

D. Florencio and C. Herley, A large-scale study of web password habits, Proceedings of the 16th international conference on World Wide Web , WWW '07, pp.657-666, 2007.
DOI : 10.1145/1242572.1242661

N. Z. Gong and D. Wang, On the security of trustee-based social authentications. Information Forensics and Security, IEEE Transactions on, vol.9, issue.8, pp.1251-1263, 2014.

J. Hamerník, Autentiza?ní metody pou?ívané k obnov? p?ihla?ovacího hesla, Czech), Masaryk University (2014), [Online; Accessed, 2016.

M. Honan, How Apple and Amazon Security Flaws Led to My Epic Hacking. http://www.wired.com/2012/08/apple-amazon-mat-honan-hacking, 2012.
DOI : 10.7312/star16075-030

M. Just and D. Aspinall, Personal choice and challenge questions, Proceedings of the 5th Symposium on Usable Privacy and Security, SOUPS '09, 2009.
DOI : 10.1145/1572532.1572543

Y. S. Lee, N. H. Kim, H. Lim, H. Jo, and H. J. Lee, Online banking authentication system using mobile-OTP with QR-code, Computer Sciences and Convergence Information Technology (ICCIT) 5th International Conference on, pp.644-648, 2010.

K. C. Liao and W. H. Lee, A Novel User Authentication Scheme Based on QR-Code, Journal of Networks, vol.5, issue.8, pp.937-941, 2010.
DOI : 10.4304/jnw.5.8.937-941
URL : http://ojs.academypublisher.com/index.php/jnw/article/viewFile/0508937941/2055/

A. Moallem, Did You Forget Your Password?, pp.29-39, 2011.
DOI : 10.1145/1355284.1355288

A. Rabkin, Personal knowledge questions for fallback authentication, Proceedings of the 4th symposium on Usable privacy and security, SOUPS '08, pp.13-23, 2008.
DOI : 10.1145/1408664.1408667

S. Schechter, A. B. Brush, and S. Egelman, It's No Secret. Measuring the Security and Reliability of Authentication via “Secret” Questions, 2009 30th IEEE Symposium on Security and Privacy, pp.375-390, 2009.
DOI : 10.1109/SP.2009.11

S. Schechter, S. Egelman, and R. W. Reeder, It's not what you know, but who you know: a social approach to last-resort authentication, Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, pp.1983-1992, 2009.
DOI : 10.1145/1518701.1519003