Perhaps you should try some spelling variations:
"Smart skills surveys." » "Smart skills survey."
"smart skills series." » "smart skills survey.", "math skills series.", "soft skills series."
"Smart soil surveys." » "Smart social surveys.", "Smart school surveys.", "Smart point 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 surveys."))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"smart skills series.\") or (((\"Smart soil surveys.\") OR (\"Smart skills surveys.\"))))~".
• Removing quotes may allow a broader search: (( smart skills series. ) or ((( Smart soil surveys. ) OR ( Smart skills surveys. ))))~.
• Adding a wildcard symbol may retrieve word variants: (("smart skills series.") or ((("Smart soil surveys.") OR ("Smart skills surveys."))))*.