Perhaps you should try some spelling variations:
actors research » factors research, actions research, author's research
iea research » a research, 2 research, 2.1 research
multi actors » multi actor, multi acteurs, multi factor
multi iea » multi area, multi head, multi item
july 2007 » july 2013, july 2012, july 2020
july 2008 » july 2013, july 2012, july 2020

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( multi iea research : july 2007 ) OR ( multi actors research : july 2008 ))~.
• Adding a wildcard symbol may retrieve word variants: (( multi iea research : july 2007 ) or ( multi actors research : july 2008 ))*.