Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
DOUBLE MODAL AUXILIARIES
I might could be able to visit later on. George had ought to pay you back for the loan. She shouldn’t ought to be here. Nearly all these double modals are from the spoken language only, and most of them have some regional limitations too: might can and might could have usually been limited to Southern and South Midland dialects, and hadn’t ought is probably mainly Northern. Only the combinations with ought and especially the negative combinations such as shouldn’t ought and hadn’t ought are much heard these days. They are Nonstandard, and you should not or shouldn’t or ought not to or oughtn’t to use them except in the most Casual circumstances wherein your hearers regularly use them too. See MODAL AUXILIARIES.
