Perhaps you should try some spelling variations:
"multiple vaccines research : july 2009" » "multiple access research : july 2009", "multiple crises research : july 2009", "multiple faces research : july 2009", "multiple vaccine research : july 2009", "multiple practices research : july 2009", "multiple accidents research : july 2009", "multiple vaccines research : july 2008", "multiple vaccines research : july 2007", "multiple vaccines research : july 2019"
"multi client research : july 2011" » "multi accident research : july 2011", "multi climate research : july 2011", "multi current research : july 2011", "multi agent research : july 2011", "multi plant research : july 2011", "multi client research : july 2013", "multi client research : july 2012", "multi client research : july 2015"

Try widening your search to All Fields.

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 2009") or ("multi client research : july 2011"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("multiple vaccines research : july 2009") OR ("multi client research : july 2011")).
• Removing quotes may allow a broader search: (( multiple vaccines research : july 2009 ) or ( multi client research : july 2011 )).
• Adding a wildcard symbol may retrieve word variants: (("multiple vaccines research : july 2009") or ("multi client research : july 2011"))*.