Perhaps you should try some spelling variations:
professionnelle services » professionelle services, professionellen service, professionnelle efficaces
channel formation » channel estimation, channel modulation, channel function
professional » professionals

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "channel formation ((professionnelle services) OR (professional services))".
• Adding a wildcard symbol may retrieve word variants: channel formation ((professionnelle services) OR (professional services))*.