Perhaps you should try some spelling variations:
case extension » base extension, casl extension, based extension
circuits case » circuits based, circuits fast, circuits cat
large spaces » larger spaces, gauge spaces, large scales
safe spaces » state spaces, shape spaces, scale spaces
large space » large sparse, large scale, large surface

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

• Performing a fuzzy search may retrieve terms with similar spellings: communication circuits case extension ((((large spaces) or (safe spaces))) or (large space))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: communication circuits case extension ((((large spaces) OR (safe spaces))) OR (large space)).
• Adding a wildcard symbol may retrieve word variants: communication circuits case extension ((((large spaces) or (safe spaces))) or (large space))*.