Redirect Notice
 The previous page is sending you to https://www.sciencedirect.com/science/article/pii/S0007153685800334/pdf?md5=84f017f09837e65393bddb4dce987814&pid=1-s2.0-S0007153685800334-main.pdf.

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