Here is an excellent way to find clarinet music, books, recordings, etc.: WorldCat.org. (Actually, you can find pretty much anything.)
Worldcat.org is online catalog of 1. 5 billions items contained in the collections of 72,000 libraries in 170 countries and territories (as per the WorldCat.org site and Wikipedia).
It is easy to use (at least in the USA). At WorldCat.org, just type in what you are looking for in the Search Everything box and a list of items will appear. Click on the correct item you want and a list of the nearest libraries that have it will pop up.
Take the newly-acquired information on your item to your local university library (or most any library) and they will help you do Interlibrary loan. (You may also be able to call or email your library.) At my university it takes a week or two to get things, but once it arrives they usually give you three weeks with the item (more with renewals). (Interlibrary loan is a powerful tool that no one ever thinks about.) Be aware they may charge you a small fee, but very often it is free, especially for students and faculty.
For example, I just did a WorldCat.org search on the wonderful, but, very unfortunately, out of print Leon Russianoff Clarinet Method. It is available at the Murray State University Library, 84 miles from my house in Cape Girardeau, Missouri. Of course, not all items at all libraries circulate, but you can most likely find a library out there somewhere that will help you out.
ClarinetMike says, “Check it out!”