Perhaps you should try some spelling variations:
"smart skills series." » "smart skills surveys.", "math skills series.", "soft skills series."
"smart skills survey." » "math skills survey.", "soft skills survey."
"Smart soil surveys." » "Smart social surveys.", "Smart school surveys.", "Smart skills surveys."
smart soil » smart social, smart school

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: (("smart skills series.") OR ((("Smart soil surveys.") OR ("smart skills survey."))))~.
• Removing quotes may allow a broader search: (( smart skills series. ) or ((( Smart soil surveys. ) or ( smart skills survey. ))))~.
• Adding a wildcard symbol may retrieve word variants: (("smart skills series.") or ((("Smart soil surveys.") or ("smart skills survey."))))*.