The rediscovery of the original manuscripts of Max Reger’s works for violin, viola and violoncello op. 131a–d in the Prague Conservatory Library represents a small sensation. These late works for solo strings dating from 1914 and 1915, the last of which appeared only posthumously, were previously known only from their first prints. The three duos op. 131b for two violins were composed within a few days, shortly after Easter 1914; it is particularly in this case that access to Reger’s autograph is of great value in terms of providing insight into the genesis of the works.