Perhaps you should try some spelling variations:
"residual research studies" » "residues research studies", "residue research studies", "resident research studies"
"residual research study" » "residues research study", "residue research study", "resident research study"
"rescue search series" » "rescue sar series", "rescue search services", "rescue research series", "rescue search queries"

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: "((\"rescue search series\") OR (((\"residual research studies\") OR (\"residual research study\"))))".
• Removing quotes may allow a broader search: (( rescue search series ) OR ((( residual research studies ) OR ( residual research study )))).
• Adding a wildcard symbol may retrieve word variants: (("rescue search series") OR ((("residual research studies") OR ("residual research study"))))*.