Perhaps you should try some spelling variations:
commonwealth era » commonwealth a, commonwealth mr, commonwealth draft
somis professor » hollis professor, paris professor, sometime professor
aus professor » als professor, laud's professor, famous professor

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: ((somis professor) OR (aus professor)) of commonwealth era.
• Adding a wildcard symbol may retrieve word variants: ((somis professor) or (aus professor)) of commonwealth era*.