From what I can understand from the National Library of Netherlands website, Gerrit Jan's Sonata is in 3 movements : Allegro agitato, Andante, Moderato. They have what seems to be the first edition by Th. J. Roothaan, as well as a modern edition by the Nederlands Muziek Instituut http://www.nederlandsmuziekinstituut.nl/en/publications/sheet-music/765-eijken-gj-van-sonate-in-f-klein-voor-piano-en-viool-opus-5-1852