Perhaps you should try some spelling variations:
location research » locations research, education research, action research
vaccine research » medicine research
multi location » multi option, multiple locations, multiplication _
multi vaccine » anti vaccine, multiple vaccines
july 2006 » july 2008, july 2007, july 2009

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( multi vaccine research : july 2006 ) or ( multi location research : july 2013 ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( multi vaccine research : july 2006 ) OR ( multi location research : july 2013 )).
• Adding a wildcard symbol may retrieve word variants: (( multi vaccine research : july 2006 ) or ( multi location research : july 2013 ))*.