Perhaps you should try some spelling variations:
communication recreation » communication preservation, communications regulation, communication recognition
recreation safety » recreation areas, radiation safety, recreation fast
dspaces » ddspaces
dddspaces » ddddspaces
ddddspaces » dddddspaces
space » dspace

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

• Performing a fuzzy search may retrieve terms with similar spellings: communication recreation safety ((dspaces or dspaces) or (dddspaces OR ddddspaces)) euclidean space~.
• If you are trying to use Boolean operators, they must be ALL CAPS: communication recreation safety ((dspaces OR dspaces) OR (dddspaces OR ddddspaces)) euclidean space.
• The words AND, OR and NOT may confuse the search; try adding quotes: "communication recreation safety ((dspaces or dspaces) or (dddspaces OR ddddspaces)) euclidean space".
• Adding a wildcard symbol may retrieve word variants: communication recreation safety ((dspaces or dspaces) or (dddspaces OR ddddspaces)) euclidean space*.