http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6TGJ-4CYR55X-1-1&_cdi=5256&_user=119223&_pii=S0924013604008490&_origin=&_coverDate=03%2F20%2F2005&_sk=998399997&view=c&wchp=dGLzVzb-zSkWB&md5=3b6222e8013c802ecaa6746e661eb5f1&ie=/sdarticle.pdf