Perhaps you should try some spelling variations:
"depth accident research : july 2011" » "depth current research : july 2011", "depth recent research : july 2011", "depth accident research : july 2013", "depth accident research : july 2012", "depth accident research : july 2015"
"meet vaccine research : july 2006" » "meet medicine research : july 2006", "media vaccine research : july 2006", "ant vaccine research : july 2006", "mr vaccine research : july 2006", "meet vaccine research : july 2008", "meet vaccine research : july 2007", "meet vaccine research : july 2009"

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: (("depth accident research : july 2011") or ("meet vaccine research : july 2006"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("depth accident research : july 2011") OR ("meet vaccine research : july 2006")).
• Removing quotes may allow a broader search: (( depth accident research : july 2011 ) or ( meet vaccine research : july 2006 )).
• Adding a wildcard symbol may retrieve word variants: (("depth accident research : july 2011") or ("meet vaccine research : july 2006"))*.