Correspondence, manuscript, and printed materials of Kees. There are fourteen letters from Kees to Herbert Cahoon, twelve letters from James T. Farrell to Kees, the manuscript of Kees' THE LAST MAN, and announcements and clippings by and about Kees.

The William Hobart Mitchell Papers are comprised of five series: Correspondence, Music Career, Writings, Personal Papers and Teaching Materials. The largest body of correspondence contains letters written between Mitchell and his first wife, Claramary (Clerky), that document their courtship in the mid 1930s as well as William's time in the Civilian Public Service unit during World War II. The majority of the letters relate to William's musical tours of universities and colleges throughout the United States between the late 1940s and the early 1960s. This group of letters shares William's experiences during his travels as well as documenting Claramary's everyday life in New York City and later in Rye, New York.

This collection of autographed inscriptions and letters from noted 19th century musicians was assembled by Mason. The material includes the signatures of 85 composer, performers, and other musical people, most of whom were Dr. Mason's contemporaries and personal friends. There are 103 items the majority of which are bits of music in script with signatures, and a few autograph letters to Mason. Among those represented are Berlioz, Jenny Lind, Franz Liszt, MacDowell, Paderewski, Rubinstein, Saint-Saens, Samaroff, and the Schumanns.