Writers in music typically use the style guidelines of the Modern Language Association (MLA) to format a paper, to document sources within the paper, and to cite sources at the end of the paper. Those guidelines are set forth in the MLA Handbook for Writers of Research Papers, 7th ed. (2009).
In addition, specific information about writing in music can be found in D. Kern Holoman, Writing about Music: A Style Sheet, 2nd ed. (2008), and Jonathan Bellman, A Short Guide to Writing about Music, 2nd ed. (2006).
Related topic:
Citing sources in MLA style