The collection includes music scores of Hugo Alpen's compositions, song books and text books containing Alpen's work, letters of Alpen's wife Sarah to her daughter (Ida Crisp), photographs, cuttings and a cutting album. Attached to many items are typescript notes of explanation written by Paul Alpen in 1971. Also included is Paul Alpen's translation, in 1957 for the Cabinet Secretariat of the Prime Minister's Department, of a theoretical study of the European Economic Community written in Dutch by P. J. Verdoorn and entitled 'An economic integration of Europe: a study of its background and consequences' (The Hague, 1952).