Redirect Notice
The previous page is sending you to
https://www.sciencedirect.com/science/article/pii/S0016787830800105/pdf?md5=d8d2e49736713b58714352cf6f27fa93&pid=1-s2.0-S0016787830800105-main.pdf
.
If you do not want to visit that page, you can
return to the previous page
.