[1. Public Knowledge Project. Open Journal Systems. Available at: https://pkp.sfu.ca/ojs/ Accessed: October 6, 2014.]Search in Google Scholar
[2. Ubuntu. The leading OS for PC, tablet, phone and cloud. Available at: http://www.ubuntu.com/ Accessed: October 6, 2014.]Search in Google Scholar
[3. CentOS Project. Cent Operating System. Available at: http://www.centos.org/ Àccessed: October 6, 2014).]Search in Google Scholar