Perhaps you should try some spelling variations:
diffusion reflection » discussion reflection, diffusion reaction, diffuse reflection
pollution dispersion » pollutant dispersion
dispersion reduction » dispersion prediction, dispersion predictions, dimension reduction
diffusion reduction » diffusion prediction, diffusion reaction, diffusion equation

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: (( pollutant ((diffusion reduction) OR (diffusion reflection)) ) OR ( pollution dispersion reduction )).
• Adding a wildcard symbol may retrieve word variants: (( pollutant ((diffusion reduction) or (diffusion reflection)) ) or ( pollution dispersion reduction ))*.