mình có bài báo này rất cần, muốn nhờ các bạn lấy giúp. cám ơn nhiều
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6W7N-4VT0X5Y-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1141894795&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b6c68ae0ff51fc8616c43a1841ebea81
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6W7N-4VT0X5Y-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1141894795&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b6c68ae0ff51fc8616c43a1841ebea81