Perhaps you should try some spelling variations:
"multiple imputation research : july 2009" » "multiple population research : july 2009", "multiple education research : july 2009", "multiple migration research : july 2009", "multiple imputation research : july 2006", "multiple imputation research : july 2013", "multiple imputation research : july 2012"
"multi option research : july 2009" » "multi opinion research : july 2009", "multi action research : july 2009", "multi operations research : july 2009", "mali options research : july 2009", "multiple options research : july 2009", "multi option research : july 2006", "multi option research : july 2013", "multi option research : july 2012"

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