The websites besides and below have all been confirmed as authorities. Remember to evaluate websites that you find before you rely on their authority. Useful guidelines for this may be found at Evaluating Web Pages: Techniques to Apply and Questions to Ask, a page provided by the library of UC Berkeley. Please consult Schaffer's reference librarians on this as well.
Here are two websites to practice on. If you found them (e.g., by "googling"), would you rely on them and why or why not?Example One