There are some graphs and other visuals that the author uses that seem to be research results from the last 3 years, is this source credible?

Yes.

Explanation:

As long as the research they conducted has not been proven to be wrong, then the research should still be useful.

atmospheres is the answer to your question.

explanation:

it u understand what he thought at the time and let u know more about him then what third person would of known probably. hope this : )