[13] P. Engebretson, The Basics of Hacking and Penetration Testing: Ethical Hacking and Penetration Testing Made Easy, Elsevier Inc., USA, 2011. [On-line]. Disponible en https://wqreytuk.github.io/Patrick+Engebretson+The+Basics+of+Hacking+and+Penetration+Testing,+Second+Edition+%282013%29.pdf