(April 23, 2015 at 1:40 pm)Alex K Wrote: But back on topic: is there an official authority on English or AE grammar where one would find these things?
I don't think there is a single source that has some special authority that dictates what English speakers must or should do. Oxford produces one of the better dictionaries, and very likely Oxford is a very reliable source for grammar, particularly of British English, though they are interested in "world English" as well.
"A wise man ... proportions his belief to the evidence."
— David Hume, An Enquiry Concerning Human Understanding, Section X, Part I.