Perhaps you should try some spelling variations:
political scientists » political science, social scientists
clinical scientist » clinical scientific, clinical sciences, clinical science
mark webber » mark weber, mr webber, mark weiser

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

• If you are trying to use Boolean operators, they must be ALL CAPS: mark webber (((political scientists) OR (clinical scientist))).
• Adding a wildcard symbol may retrieve word variants: mark webber (((political scientists) or (clinical scientist)))*.