Credible versus Non-credible sources

Non-Credible sources

#1 Non-credible source:

I know it is a non-credible source because:
1. The website has a ".com" address, which means that anyone could have purchased that website.
2. There are more than five ads on the page.
3. The website is not focused on my topic, chess history.
4. The author does not have a degree or credentials in chess, so I don't know if I can trust his opinion.

#2 Non-credible source.

I know it is a non-credible source because:
1. The website has a ".com" address, which means that anyone could have purchased the website.
2. The description of the website at the top of the page tells me that it's purpose is to get people to play games online and to join their website.
3. The section that's marked "learn" on their website has just a little paragraph about the history of chess and it doesn't tell you where it got any of it's information.

#3 Non-credible source.

I know this is a non-credible source because:
1. Most of the information on the page is not footnoted or doesn't have a source, so it's hard to know where the authors are getting their information from.
2. Wikipedia pages can be edited by anyone and that means people can add or delete whatever they want, so there's no telling what is correct or incorrect.
3. The webpage has a ".org" website domain, which means they are a non-profit, but they still are not as reliable as a ".edu" address.

Credible Sources

Credible source #1

I found my first credible source by searching Google Scholar. The source is a book all about the history of chess.

I know this is a credible source because:
1. The book has one author, Gerhard Josten, and after I did a quick Google search of his name I found out that he is a historian and author of chess books.
2. The book has footnotes and references that let me know where the author is getting his information.
3. The book looks like it has been carefully edited and there are no noticeable grammar or spelling mistakes.

Credible source #2

I found my second credible source by checking the "notes" section at the bottom of the Wikipedia chess page. I saw an article about the history of chess.

I know this is a credible source because:
1. It's written by one author, Dr. Ricardo Calvo, who I did a quick Google search on and found out was an International Grandmaster and chess historian.
2. Even though the website has a ".com" listing, I did a Google search of the title of the article and found it on a more credible website.
3. The description of the website that I found on the top of the page said that the purpose of the website was to explore the history of chess. Also, it doesn't look like the website is really trying to sell anything.

Credible source #3

I found my third credible source by typing in "chess origins" in Wikipedia. I ended up finding an article from encyclopedia Britannica that talked about the history of chess.

I know this is a credible source because:
1. According to the "about us" section of the website, Enyclopedia Brittanica has been around for many years and is the oldest printed encyclopedia in the world.
2. The website gives a thorough history of chess, covering a lot of different types of topics
3. The website has a professional layout and is free of grammatical or spelling errors.