Over the weekend I went through the Alto Trombone History Timeline and double-checked sources. I ended up adding several sources to the Alto Bibliography that had inadvertently been omitted (primarily 19th-century trade catalogs). With these additions, the Alto Timeline now features more than 100 primary sources, not to mention the numerous secondary sources. With the possible exception of Ken Shifrin’s excellent dissertation on the use of alto trombone in the orchestra, I don’t believe there is any other single document on alto trombone that utilizes as many primary sources.