WHAT are A.R.T. Sources?
Information sources which are:
WHY use A.R.T. Sources?
A.R.T. helps evaluate the trustworthiness of the sources for your research.
Q1. Is Wikipedia authoritative? It has citations and a list of references.
Check this description of Plato before the record was corrected:
Wikipedia is editable. Anybody can add stuff and change stuff any time. Although Wikipedia is a quick way to get a sense of something, it is not authoritative for academic research.
Read what Wikipedia has to say about hoaxes.
Q2. Are websites with .com authoritative?
Websites with .com are usually commercial or business sites. Information given may be informational but the purpose is to get readers to be interested in buying from them. Therefore, you may not have the complete set of information or there may be some bias.