Perhaps you should try some spelling variations:
"export base international power." » "export base international poverty.", "export base international ports.", "export base international panel.", "export based international power.", "export case international power.", "export bayne international power."
"upper surface irrigation schemes." » "upper scale irrigation schemes.", "upper surface irrigation scheme.", "upper surface irrigation systems.", "summer surface irrigation schemes.", "other surface irrigation schemes.", "der surface irrigation schemes."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("upper surface irrigation schemes.") or ("export base international power."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("upper surface irrigation schemes.") OR ("export base international power."))*.
• Removing quotes may allow a broader search: (( upper surface irrigation schemes. ) or ( export base international power. ))*.