1. Todorov, D.: Mechanics of User Identification and Authentication, pp. 1–18. Auerbach Publications, Boca Raton (2007)
2. Convery, S.: Network authentication, authorization, and accounting: part one. Internet Protoc. J. 10(1). [online] Cisco. Available at: https://www.cisco.com/c/en/us/about/press/internet-protocol-journal/back-issues/table-contents-35/101-aaa-part1.html. Accessed 12 Aug 2017 (2007)
3. Web.mit.edu. Kerberos: The Network Authentication Protocol. [online] Available at: https://web.mit.edu/kerberos/. Accessed 13 Aug 2017 (2007)
4. Henry, A.: The difference between two-factor and two-step authentication. [online] Lifehacker.com. Available at: http://lifehacker.com/the-difference-between-two-factor-and-two-step-authenti-1787159870. Accessed 13 Aug 2017 (2007)
5. Valve Corporation: Steam. Version 2.3.1. [Mobile app]. Google Play Store. Support.steampowered.com. (2017). Steam Guard Mobile Authenticator – Managing Your Account Features - Knowledge Base – Steam Support. [Online] Available at: https://support.steampowered.com/kb_article.php?ref=8625-wrah-9030. Accessed 15 Aug 2017 (2007)