Article1 :
http://link.springer.com/chapter/10.1007%2F978-3-642-12145-6_30
Article 2:
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4722680&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4721667%2F4722542%2F04722680.pdf%3Farnumber%3D4722680
Article 3:
http://link.springer.com/chapter/10.1007%2F978-3-642-33140-4_26
Article 4:
http://link.springer.com.www.sndl1.arn.dz/chapter/10.1007/978-3-642-33140-4_26