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Izaias, You will get a bit of differing opinion, but I disagree with the author. First, it is believed that linking to authoritative sources is a plus for SEO. Second, you do not "lose" by linking to others. What he/she is likely referring to is if you have a PA of 30 and 4 internal links to other pages along with 8 to external, less would go internally than externally.  To me, it makes no sense to worry about this as it is trivial compared to good content with quality outbound links that make sense for your audience. Then get links back to you, etc. I would not worry about it and just leave them as do follow. Best

I check the Webmasters Tools and everything is correct. The geo targeting is for Brazil. Thank you.