The way we study music is shaped by the way music is created and disseminated. Music and scholarship on music can take many forms. We call each instance of a work a manifestation. For any given performance or paper, we may need to use one or all of these formats. It may help to think about these forms sequentially, from the point at which a work is conceived.
So to do thorough research in music, you need to be able to locate, use, and evaluate printed music, various types of recordings, newspaper reviews, articles and essays in periodicals, and books.