Perhaps you should try some spelling variations:
information documents » information documentation, information requirements
concept definitions » concepts definitions, concept definition, concise definitions
information agents » information age, information access, information about
definitions causes » definition causes, definitions chapter, definitions sources
causes cures » causes cure

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((information documents) OR (information agents)) concept definitions causes cures~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((information documents) OR (information agents)) concept definitions causes cures".
• Adding a wildcard symbol may retrieve word variants: ((information documents) OR (information agents)) concept definitions causes cures*.