Perhaps you should try some spelling variations:
international convention » international cooperation, international context, international communication
root extraction » root restriction, root extract, product extraction
root extracts » root extract, shoot extracts, fruit extracts
methods links » methods linda, methods linear, methods blind
methods line » methods linear, methods linda, methods blind

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

• Performing a fuzzy search may retrieve terms with similar spellings: international convention ((root extraction) OR (root extracts)) ((methods links) or (methods line))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: international convention ((root extraction) OR (root extracts)) ((methods links) OR (methods line)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "international convention ((root extraction) OR (root extracts)) ((methods links) or (methods line))".
• Adding a wildcard symbol may retrieve word variants: international convention ((root extraction) OR (root extracts)) ((methods links) or (methods line))*.