Perhaps you should try some spelling variations:
option research » opinion research, action research, optics research
multi option » multi location, multi population, multi ratios
june 2009 » june 2007, june 2019, june 2013
june 2008 » june 2007, june 2013, june 2014
july 2006 » july 2008, july 2007, july 2009
july 2011 » july 2013, july 2012, july 2015

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

• Performing a fuzzy search may retrieve terms with similar spellings: multi option research : ((((june 2009) OR (june 2008))) or (((july 2006) or (july 2011))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: multi option research : ((((june 2009) OR (june 2008))) OR (((july 2006) OR (july 2011)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "multi option research : ((((june 2009) OR (june 2008))) or (((july 2006) or (july 2011))))".
• Adding a wildcard symbol may retrieve word variants: multi option research : ((((june 2009) OR (june 2008))) or (((july 2006) or (july 2011))))*.