Perhaps you should try some spelling variations:
profesional series » professional series, professional services, professional stories
channel formation » channel estimation, channel modulation, channel function
ciones formacion » con informacion

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: ((ciones formacion) OR (channel formation)) profesional series.
• Adding a wildcard symbol may retrieve word variants: ((ciones formacion) or (channel formation)) profesional series*.