Redirect Notice
 The previous page is sending you to https://www.sciencedirect.com/science/article/pii/S0007153665800031/pdf?md5=fadc6ec0334dbff05dc5de6608b8902f&pid=1-s2.0-S0007153665800031-main.pdf&_valck=1.

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