Be sure you are changing up your search strategy in music research & look in different databases and journals. There are many resources available through the Open Access Journals included & linked in the next section which are often also peer reviewed and easy to use online.
Remember that each database has their own limited language it's operating with, and if you're not speaking that language you could have holes in your research.
It's important to be thoughtful with your search terms and can be worth reviewing the list of database subjects when available and even applying subject filters that the databases supply.
Many of our databases, like Academic Search Ultimate, have an Advanced Search page where you should be able to access a Subject Terms Index to get a better understanding of the language you can use to search more effectively in the database, though it could be labeled something slightly different (Subject Thesaurus, Subject Headings List, etc).
Here, you can usually browse a subject list or even search within it for relevant topics to plan for what you're going to use as search terms. Often you can directly add them to your next search, if that is easiest for your searching.
With some databases, such as JSTOR, you may not see a way to include or browse their subject language before hitting the 'search' button. Instead or additionally, you may see a way to add subject limiters on the results page of your search.
Most databases have a form of this subject filter, and some could even allow you to exclude particular subjects if it is impeding your research.