Perhaps you should try some spelling variations:
multiple vaccines » multiple access, multiple crises, multiple faces
vaccines research » vaccine research, practices research, accidents research
bali climate » mali climate, daily climate, early climate
july 2011 » july 2013, july 2012, july 2015
june 2011 » june 2013, june 2014, june 2010

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( multiple vaccines research : july 2011 ) or ( bali climate research : june 2011 ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( multiple vaccines research : july 2011 ) OR ( bali climate research : june 2011 )).
• Adding a wildcard symbol may retrieve word variants: (( multiple vaccines research : july 2011 ) or ( bali climate research : june 2011 ))*.