The following did not work.
wget -r -A .pdf home_page_url
It stop with the following message:
.... Removing site.com
It may be based on a robots.txt. Try adding -e robots=off.
-e robots=off
Other possible problems are cookie based authentication or agent rejection for wget. See these examples.
EDIT: The dot in ".pdf" is wrong according to sunsite.univie.ac.at