Perhaps you should try some spelling variations:
factor research » factors research, sector research, actors research
multi factor » multi actor, multi sector, _ multifactor
july 2009 » july 2008, july 2007, july 2019
june 2009 » june 2007, june 2008, june 2019
july 2011 » july 2013, july 2015, july 2019
july 2012 » july 2013

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

• Performing a fuzzy search may retrieve terms with similar spellings: multi factor research : ((((((july 2009) or (june 2009))) or (july 2011))) or (july 2012))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: multi factor research : ((((((july 2009) OR (june 2009))) OR (july 2011))) OR (july 2012)).
• Adding a wildcard symbol may retrieve word variants: multi factor research : ((((((july 2009) or (june 2009))) or (july 2011))) or (july 2012))*.