Perhaps you should try some spelling variations:
"multiple imputations research : july 2009" » "multiple imputation research : july 2009", "multiple operations research : july 2009", "multiple population research : july 2009", "multiple institutions research : july 2009", "multiple imputations research : july 2006", "multiple imputations research : july 2013", "multiple imputations 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.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"multiple imputations research : july 2009\") OR (\"multi option research : july 2009\"))~".
• Removing quotes may allow a broader search: (( multiple imputations research : july 2009 ) OR ( multi option research : july 2009 ))~.
• Adding a wildcard symbol may retrieve word variants: (("multiple imputations research : july 2009") OR ("multi option research : july 2009"))*.