Perhaps you should try some spelling variations:
teaching learning » machine learning
learning research » teaching research, learning resources, emerging research
options research » actions research, optics research, operations research
case options » care options, lease options, scale options
july 2011 » july 2013, july 2012, july 2015
july 2006 » july 2008, july 2007, july 2009

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: (( teaching learning research : july 2011 ) OR ( case options research : july 2006 ))~.
• Adding a wildcard symbol may retrieve word variants: (( teaching learning research : july 2011 ) or ( case options research : july 2006 ))*.