Perhaps you should try some spelling variations:
information retraction » information extraction, information interaction, information abstraction
retraction systems » restriction systems, reaction systems, extraction systems
systems recent » systems report
array formulas » area formulas, harrop formulas, array format
array string » array strong, arrays strings, array sharing
array using » arrays using

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

• Performing a fuzzy search may retrieve terms with similar spellings: information retraction systems recent ((((array formulas) or (array string))) or (array using))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: information retraction systems recent ((((array formulas) OR (array string))) OR (array using)).
• Adding a wildcard symbol may retrieve word variants: information retraction systems recent ((((array formulas) or (array string))) or (array using))*.