Perhaps you should try some spelling variations:
option research » opinion research, action research, optics research
factor research » factors research, sector research, actors research
multi factor » multi actor, multi sector, _ multifactor
multi option » multi location, multi population, multi ratios
june 2011 » june 2013, june 2014, june 2010
june 2012 » june 2013, june 2014, june 2010
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 : ((june 2011) OR (june 2012)) ) or ( multi option research : july 2012 ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( multi factor research : ((june 2011) OR (june 2012)) ) OR ( multi option research : july 2012 )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( multi factor research : ((june 2011) OR (june 2012)) ) or ( multi option research : july 2012 ))".
• Adding a wildcard symbol may retrieve word variants: (( multi factor research : ((june 2011) OR (june 2012)) ) or ( multi option research : july 2012 ))*.