Perhaps you should try some spelling variations:
22stability theory » stability theory, testability theory, disability theory
instability theory » stability theory, probability theory, reliability theory
bistability theory » stability theory, disability theory, testability theory

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: %((((22stability theory) OR (instability theory))) OR (bistability theory))%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((((22stability theory) OR (instability theory))) or (bistability theory))%22".
• Adding a wildcard symbol may retrieve word variants: %((((22stability theory) OR (instability theory))) or (bistability theory))%22*.