The violinists are the worst…I can’t tell you the number of students, violinists that I’ve had who said “Yes, I will learn the seventh sonata by Reger. I will have it on my next recital.” Never.
As of now (more specifically, earlier this month), it will perhaps be at least slightly easier for some of those violinists to follow through, because there is now a free edition available on IMSLP of the work I assume Diamond was referring to: the seventh of Max Reger’s Seven Sonatas for Solo Violin, op. 91.
(Of course, the phrase “seventh sonata by Reger” is hardly unambiguous, even when restricted to the realm of the violin: Reger had earlier published a collection of four solo sonatas as his op. 42, and in addition there is also his series of sonatas for violin and piano — a genre also commonly called “violin sonata”. Thus, in addition to op. 91 no. 7, “seventh [violin] sonata by Reger” could conceivably mean op. 91 no. 3, op. 103b no. 2, or even op. 42 no. 4. However, op. 91 no. 7 seems the most likely candidate.)
This rectifies a long-standing omission in the IMSLP catalog, which since 2011 has included the first six sonatas of op. 91, but, mysteriously, not the seventh, thereby tantalizing visitors who came in search of the famous Chaconne.