Cobra Forums

I just googled about Cobra and had found the book on http://www.amazon.co.uk/Cobra-programmi ... 6132215611
is this book is exist?

Pretty weird. It seems pretty fishy though -- for instance the blurb in the red dot:
"High Quality Content by WIKIPEDIA articles!"

Are there enough articles on Cobra at WIKIPEDIA to warrant a book?

That's one of those book publishers that scrapes free content off the web, prints it and charges for it. You'll notice that the title is identical to the wikipedia page:

http://en.wikipedia.org/wiki/Cobra_(programming_language_from_Cobra_Language_LLC)

It's a scam/rip-off.

Instead, look at http://cobra-language.com/docs/how-to-learn/.