Redirect Notice
 The previous page is sending you to http://www.sciencedirect.com/science/article/pii/0034666790900032/pdf?md5=7a56fe48d39b3c623f50840743902430&pid=1-s2.0-0034666790900032-main.pdf.

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