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I think Google has documented this pretty clear on the page describing how to Use a sitemap to indicate alternate language pages. NOt only for languages, but also combinations of languages and regions i.e. Switzerland (de-ch), Ireland (en-ie) and so on. The downside on this is that must create a separate url element for each URL.

Finally, i decided to do the next: Delete all pages from my site with filters (i have the option and it wasn't a problem) Delete URL using GWT individually It works!

In my opinion: No, you should not. The result will be that those URLs are indexed but with a standard description to the effect that google knows the URL exists but not what is behind it; titles may be taken from links or past data. Canonical is the way to go. Regards Nico