Yanyan Yang Charles U. Martel Zhi (Judy) Fu Shyhtsun Felix Wu IPsec/VPN security policy correctness and assurance. 275-289 2006 15 J. High Speed Networks 3 http://iospress.metapress.com/openurl.asp?genre=article&issn=0926-6801&volume=15&issue=3&spage=275 db/journals/jhsn/jhsn15.html#YangMFW06