Perhaps you should try some spelling variations:
designing effective » developing effective
effective problems » effective process, effectiveness problems, incentive problems
under states » under state, gender status, andean states
under stokes » und stokes, under stress, under state
historic » historical, histories, history

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

• Performing a fuzzy search may retrieve terms with similar spellings: historic designing effective problems ((under states) or (under stokes)) case studies.~.
• If you are trying to use Boolean operators, they must be ALL CAPS: historic designing effective problems ((under states) OR (under stokes)) case studies..
• Adding a wildcard symbol may retrieve word variants: historic designing effective problems ((under states) or (under stokes)) case studies.*.