Almost every instrument has at least one instructional book in the collection. Search OneSearch to see where to find these on the shelves (most are in the score section, but some are in the General 1st floor shelves.
Many expert musicians have instruction videos online.
Start with the Garland Encyclopedia of World Music--find the geographical location and look the instrument up in the index.
There are several other good world music encyclopedias on the shelves and online.
Every instrument has several books covering the topic in-depth; search OneSearch and WorldCat.
Many instruments have credible information online, including sites relating the instrument to music therapy--be sure to evaluate the authority.