1. Protecting secret keys with personal entropy
2. Phen-Lan Lin, Li-Tung Weng and Po-Whei Huang, “Graphical passwords using images with random tracks of geometric shapes,” 2008 Congress on Images and Signal Processing. 2008.
3. Ukasz Chmielewski1, Jaap-Henk Hoepman, Peter van Rossum. Client-Server Password Recovery.
4. Charles Miller. Password Recovery. 20th October 2002
5. Biddle R., Chiasson, S., Oorschot, P.C.: Graphical Passwords: Learning from the First Twelve Years. (2010)