Perhaps you should try some spelling variations:
recursion library » section library, recursion summary, equation library
vision library » design library, vision linear, visual library
gson library » open library, own library, town library

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: theory AND ((recursion library) OR (((vision library) OR (gson library)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "theory and ((recursion library) or (((vision library) OR (gson library))))".
• Adding a wildcard symbol may retrieve word variants: theory and ((recursion library) or (((vision library) OR (gson library))))*.