Talvez debería tentar con algunhas variantes ortográficas:
communication collision » communication commission, communication cohesion, communication collections
collision based » collocation based, collision system, collision cables
based extension » based extraction
using sparse » using spss

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: communication collision based extension ((using sparse) OR (using stochastic))~.
• Adding a wildcard symbol may retrieve word variants: communication collision based extension ((using sparse) or (using stochastic))*.