The preface by Christin Heitmann provides illuminating background information. Haydn did not assign the nickname ''Sun Quartets'': it alludes to an edition of the time, in which the title page was decorated with a rising sun. The Quartets op. 20 are the last series in a group of earlier string quartets, but are clearly ahead of their time. The demanding fugues which close three of the six quartets are a particular structural feature.? The study edition HN 9208 complements the parts of the String Quartets op. 20.