Perhaps you should try some spelling variations:
research theories » research theory, research topics, research three
research series » research services, research studies, research service
research themes » research trends, research theory

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: imiscoe ((research series) OR (((research theories) OR (research themes)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "imiscoe ((research series) or (((research theories) OR (research themes))))".
• Adding a wildcard symbol may retrieve word variants: imiscoe ((research series) or (((research theories) OR (research themes))))*.