How does a person get an entry on Britannica, Encyclopedia.com etc. ? The person has a Wikipedia page and news references. Thanks!
Like @celtschk says in a comment, traditional encyclopedias like Britannica have professional editors. It is their task to decide what gets an entry and what doesn't.
This is different from Wikipedia, which is edited by anybody and everybody willing.
Since traditional editors have only that many hours in a day, and there's only that many of them, more prioritising goes into picking entries in a traditional encyclopedia. For the same reason, those entries change more slowly.
The price Wikipedia pays for everybody being able to add entries is that mistakes enter more easily. They can also be corrected more easily, of course.
For Wikipedia it is notability.
If an entry is make for someone who is not notable enough, there is a good chance that the entry will be deleted. And the check is made on how many acceptable sources there are for said person.
Printed encyclopedia follow the same kind of rules but mostly require a higher level of notability or more published references to the person before they get included.
With Internet what it is these days it may well be a combination of (a given number of) printed and internet appearances.
Not much said person can do about it.