http://www.ms.sapientia.ro/~manyi/teaching/java/eloadas7.pdf
http://www.cs.ubbcluj.ro/~laura/webprg09-10/Foliak/11_Struts2_keretrendszer.pdf
http://www.tutorialspoint.com/struts_2/struts_pdf_version.htm
http://www.tutorialspoint.com/struts_2/struts2_tutorial.pdf