Perhaps you should try some spelling variations:
resource research » resources research, resource search, source research
residue research » residues research, residual research, rescue research
research series » research services, research theories, research studies

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: (( resource research series ) OR ( residue research series )).
• Adding a wildcard symbol may retrieve word variants: (( resource research series ) or ( residue research series ))*.