Perhaps you should try some spelling variations:
"multi educational research : july 2006" » "maxi educational research : july 2006", "multi generational research : july 2006", "multi national research : july 2006", "multi educational research : july 2008", "multi educational research : july 2007", "multi educational research : july 2013"
"anti vaccine research : july 2009" » "anti medicine research : july 2009", "ant vaccine research : july 2009", "active vaccine research : july 2009", "aids vaccine research : july 2009", "anti vaccine research : july 2008", "anti vaccine research : july 2007", "anti vaccine research : july 2019"

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: (("multi educational research : july 2006") OR ("anti vaccine research : july 2009"))~.
• Removing quotes may allow a broader search: (( multi educational research : july 2006 ) or ( anti vaccine research : july 2009 ))~.
• Adding a wildcard symbol may retrieve word variants: (("multi educational research : july 2006") or ("anti vaccine research : july 2009"))*.