Perhaps you should try some spelling variations:
channels information » channel information, change information, changed information
profesional services » professional services, professional service, professional series
channel formation » channel estimation, channel modulation, channel function

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