[romaprince]

Nhờ các anh lấy dùm các bài báo sau :

http://www.springerlink.com/content/q3p168788212066v/

http://www.springerlink.com/content/f447r40344461656/

http://www.springerlink.com/content/675872uj0635j140/

http://www.springerlink.com/content/h07q61438l611245/