Perhaps you should try some spelling variations:
"multiple vaccines research : july 2006" » "multiple access research : july 2006", "multiple crises research : july 2006", "multiple faces research : july 2006", "multiple vaccine research : july 2006", "multiple practices research : july 2006", "multiple accidents research : july 2006", "multiple vaccines research : july 2008", "multiple vaccines research : july 2007", "multiple vaccines research : july 2009"
"multi cultural research : july 2012" » "multi agricultural research : july 2012", "multi cultural resources : july 2012", "_ multicultural research : july 2012", "a multicultural research : july 2012", "6 multicultural research : july 2012", "multi cultural research : july 2013"

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 2006") or ("multi cultural research : july 2012"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("multiple vaccines research : july 2006") OR ("multi cultural research : july 2012")).
• Removing quotes may allow a broader search: (( multiple vaccines research : july 2006 ) or ( multi cultural research : july 2012 )).
• Adding a wildcard symbol may retrieve word variants: (("multiple vaccines research : july 2006") or ("multi cultural research : july 2012"))*.