Fonds consists of personal correspondence, newspaper clippings and manuscripts; as well as, memorial tributes, cards and letters of sympathy pertaining to the passing of Sonthoff. The fonds is arranged in the following series: Correspondence, Essays and Criticisms and Memorial Tributes.

The fonds includes the following series: correspondence, theses, speeches, lecture notes, printed materials, clippings, photographs, student memorabilia and manuscripts. Photographs are stored separately.