Yeah, I was thinking you might have better luck searching for something about learning or teaching, depending what you're looking for in music.
Hi Bob,
if the literature wished by th OP (scientific articles, theses, works etc. to a SPECIFIC TOPIC) is too specific, or the OP has got wishes which cannot (or only under difficulties for him) be fulfilled by the "normal" Databases (core, webarchive, google scholar, google, all of the special freely searchable catalogs like hathi trust, digital libraries, "normal" periodicals' databases (like the ZDB (journal-database) or the "EZB" ) or other national licensed, free databases concerning digitizing of sources, EROMM, or digital libraries of any kind, plus virtual libraries, and many others, meta-search-engines or clustering-engines ), then we have to "step up" a level.
I dislike very much to step this level up, because I think with enough knowledge about the mentioned ones we can get good results.
The RILM should be known? pls. read the description:
https://www.sim.spk-berlin.de/en/rilm_349.htmlbut, unfortunately, the online-RILM isn't free.
But what about the RIPM ?
https://www.ripm.org/seems to be not free either.
Other services, like, e.g., current contents / online contents / web of science and others of that kind exist, too, which evaluate / index scientific periodicals
by content / topics, and they evaluate / index academic works, too. But unfortunately, they aren't free, either.

Some libraries are, (at least in Germany) appointed "special collection-area"- libraries, and most of these "specialized" libraries, aside from their normal purpose and function, evaluate very thoroughly the scientific literature belonging to their special area. But, as I said, access to the mentioned "content"-services isn't free . Libraries, though, sometimes offer free access, but only from inside the library. Otherwise we'll have to register...
Another way, of course (and that should be
our way, on an internet-forum), is, to check out for any other interesting type of bibliography for our desired wishes, and use the free catalogs and DBs to "suck" the maximum we can, from them. (Free fulltexts, at once downloadable.)
And there are printed guides to reference material, in libraries, or printed current bibliographies of scientific journals, too, and current printed dissertation- / theses- bibliographies, and that's in every country so.
In my opinion, via the -free- databases or bibliographies, catalogues etc. which are easily and freely accessible from our houses or work, we may indeed sometimes have to "walk a longer way". But even then we can retrieve good results, if we are persistent researchers and investigators.
Only for highly specialized and highly actual newest latest academic works which are, themselves, not freely accessible, we have to use the "not free" resources. Because otherwise we won't get the documents easily and without waiting (waiting until they become freely accessible somewhen ). Imho.
Cordially, and many greetings from 8_octaves!