Who is selling nuts?

I´m trying to develop a litlle strategy using channels. So, I´m researching about all developed strategies.

But i found this nice sorprise

First, pls check this Investopedia article

Then, check this another one article

And this one is a mix

However, I have the book of John Murphy, Technical Analysis of the financial Markets and in page 470 keltner channels are explained in detail confirming explanation in the second article.

Murphy is considered a "last word" in tech analysis, but Investopedia is one of the most visited websites about trading and it supposes to be serious.

So. Who is wrong?