Perhaps you should try some spelling variations:
"multiple migration research : july 2009" » "multiple migrations research : july 2009", "multiple mediation research : july 2009", "multiple imputation research : july 2009", "multiple operations research : july 2009", "multiple education research : july 2009", "multiple migration research : july 2008", "multiple migration research : july 2007", "multiple migration research : july 2019"
"multiple options research : july 2013" » "multiple locations research : july 2013", "multiple positions research : july 2013", "multiple solutions research : july 2013", "multiple actions research : july 2013", "multiple optics research : july 2013", "multiple operations research : july 2013"

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: (("multiple migration research : july 2009") OR ("multiple options research : july 2013"))~.
• Removing quotes may allow a broader search: (( multiple migration research : july 2009 ) or ( multiple options research : july 2013 ))~.
• Adding a wildcard symbol may retrieve word variants: (("multiple migration research : july 2009") or ("multiple options research : july 2013"))*.