Redirect Notice
The previous page is sending you to
http://www.sciencedirect.com/science/article/pii/S0167569997011468/pdf?md5=3f2df125d5f774ad4a5ad79abc4a48b1&pid=1-s2.0-S0167569997011468-main.pdf&_valck=1
.
If you do not want to visit that page, you can
return to the previous page
.