In addition to the resources listed below, check the library catalog for other books on music education.
One series you may wish to consult is Teaching Music through Performance. Each volume has several chapters on teaching technique and other topics.
Here are just a few titles that you may wish to check out for doing research. Other ebooks can be found in the library's catalog, or you might go to the EBSCO ebooks database directly.
Although these databases are not strictly music-related, you may find them helpful to research topics that relate to music and music education.