Perhaps you should try some spelling variations:
"arthur robert van hippel" » "arthur robert v hippel", "arthur robert von hippel", "arthur robert van impel"
"arthur robert van poppel" » "arthur robert v poppel", "arthur robert van koppen", "arthur robert van gompel", "arthur robert von popper"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"arthur robert van hippel\") OR (\"arthur robert van poppel\"))".
• Removing quotes may allow a broader search: (( arthur robert van hippel ) OR ( arthur robert van poppel )).
• Adding a wildcard symbol may retrieve word variants: (("arthur robert van hippel") OR ("arthur robert van poppel"))*.