Perhaps you should try some spelling variations:
performance series » performance studies, performance size
animal performance » annual performance, fiscal performance, social performance
improving thermal » improving external, improving erm, improving federal
improving animal » improving initial, improving optimal, improving criminal

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( Improving animal performance series. ) or ( improving thermal performance series. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( Improving animal performance series. ) OR ( improving thermal performance series. )).
• Adding a wildcard symbol may retrieve word variants: (( Improving animal performance series. ) or ( improving thermal performance series. ))*.