I see there are actually a couple of books that pop up on googlebooks dealing specifically with auxiliary do that were published back in the 50 s I m going to attempt an interlibrary loan to see if they re worth anything as nothing from them seems available online although a few papers in JSTOR and WILEY draw on data from them Could be a decent source I actually did get to read through the ones listed above but none of these are truly great sources in my view for the entire topic My goal in looking through them was to mainly see if they used the term emphatic mood and if so whether they applied it as a means of conveying emphasis and further how they then referenced auxiliary do in this sense Aside from the usual issue of no one ever having fully bothered to create a decent consensus on mood as a category and within that a standardized naming scheme for moods the biggest problem I have with most of these sources is that they seem to assume that non do expressions of emphatic mood via emphasis of other elements is understood yet none of them actually include such a statement asserting such Mulvey refers to such expression in addition to do via auxiliaries in general with examples of emphatic will be and a few others all established by providing vocal emphasis to those elements Beard lists emphatic mood along with a slew of other functions conveyed via auxiliary verbs in general but doesn t preclude the emphatic nor any of the other things he s listed from non auxiliary expression Huddleston seems to infer the use of emphasis in conveying emphatic mood by referring to examples that include neither do nor other auxiliaries but since he doesn t actually explicitly mark his examples for whatever he is referring to them doing I suppose he thinks his observations are obvious in each there s no concrete way of knowing precisely what he is pointing to Google turns up thousands of grammars ESL primers and language learning websites that all discuss the use of do in conveying the emphatic mood but again just seem to assume the reader knows that emphasis is the means while when needed do is the vehicle Their wording seems to again point to some presupposed awareness that stressing the desired element is how you convey the emphatic usually showing examples with non verbal elements and then other auxiliaries emphasized before stating that do support comes into play when no other auxiliary is present They also provide zero sources so are worth little more than reference value