Redirect Notice
 The previous page is sending you to https://www.sciencedirect.com/science/article/pii/S0932473996800046/pdf?md5=ae6b94294fae9e0c26431861c2e2079e&pid=1-s2.0-S0932473996800046-main.pdf.

 If you do not want to visit that page, you can return to the previous page.