Redirect Notice
 The previous page is sending you to https://www.sciencedirect.com/science/article/pii/S0007153676800563/pdf?md5=bdbf90c3862dd742e4d9d1eb23614042&pid=1-s2.0-S0007153676800563-main.pdf.

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