Encyclopedias and dictionaries are really good places to start, especially if you are just beginning a project and want to gain an overview of your topic and put it in context. Many encyclopedias have excellent bibliographies that can help you find more sources to explore.
There are myriad music dictionaries and encyclopedias. Depending on what topic you are researching you may need a very specialized one or a more general one. A few of the best general ones are listed below.
The Grove Dictionary of American Music by See also the series of Oxford Handbooks relating to music education.
Articles on particular aspects of music education can be found in the encyclopedias listed above. Below are a few to get you started.
Below is a list of education encyclopedia not specific to music. Many are online, but those that are in print can be found in the Social Sciences, Health, and Education Library located on the first floor of the Main Library building.
Encyclopedia of Education by 
Encyclopedia of Multicultural Education by 
