Perhaps you should try some spelling variations:
"call options research : july 2006" » "call operations research : july 2006", "call opinion research : july 2006", "call national research : july 2006", "call option research : july 2006", "real options research : july 2006", "call options research : july 2013", "call options research : july 2012", "call options research : july 2011"
"scale action research : july 2009" » "scale national research : july 2009", "state action research : july 2009", "scale adoption research : july 2009", "take action research : july 2009", "scale action research : july 2013", "scale action research : july 2012", "scale action research : july 2011"

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: (("scale action research : july 2009") OR ("call options research : july 2006"))~.
• Removing quotes may allow a broader search: (( scale action research : july 2009 ) or ( call options research : july 2006 ))~.
• Adding a wildcard symbol may retrieve word variants: (("scale action research : july 2009") or ("call options research : july 2006"))*.