Who is responsible for these pages? Wikipedians. This is a collaborative endeavor. Scores of people have contributed to different parts of this project, and anyone can do so. Including you! All you need to know is how to edit a page.
You can learn who is responsible for the most recent versions of any given page by going to the bottom of the page and clicking on the "View other revisions" link you'll find there.
But remember, if you spot an error in the latest revision and you don't correct it, then you share responsibility for the error. So be bold in updating pages.