These sources, including a number of treatises and objects which are now lost, serve as important indicators and records of the knowledge ('ilm) production at the time. For instance, the introduction lists the names of 3 authors (Ibn Kunasa, Ibn al-'Arabi, Abu Hanifa al-Dinawari) and their treatises concerning pre-Islamic Bedouin traditions, all of which are now lost. Chapters The Book of Fixed Stars follows the 48 Ptolemaic constellations described in the Almagest, with a chapter dedicated to each individual constellation. Each chapter is split into 4 subsections. Ptolemaic constellations Each chapter begins with a description of the specified constellation and the stars that make up each grouping, thus departing from the Almagest and its concern for describing the iconographical origins of each constellation outline in Greek mythology. Here, al-Sufi is often critical of Ptolemy for seemingly prioritising the constellation outline over the actual stars in a constellation grouping, with some stars being overlooked. In making these revisions, al-Sufi was able to determine the boundaries for each constellation's star grouping. Indigenous Arabic constellations Al-Sufi continues his description of the specified constellation in terms of the Pre-Islamic Bedouin constellations and star groupings, noting their positions and distance to the Ptolemaic constellation stars. Illustrations In this section, al-Sufi presents 2 different views/illustrations of the specified Ptolemaic constellations: the constellation viewed in the sky from the ground and the constellation as viewed on top of a globe. The latter view can be explained by accounts of al-Sufi's drawing process, whereby the author carefully fitted a thin sheet of paper on top of a celestial globe and then directly copied the constellation outlines and star positions from the engravings. The inclusion of this globe view of each constellation also suggests that the Books of Fixed Stars was intended to be used by owners of celestial globes, and many surviving globes from the 13th and 14th Centuries include statements attesting to the treatise as an influential source. Although al-Sufi names several sources in his introduction which contributed to the book's illustrations, none of these treatises nor celestial globes survive. These illustrations represent another important departure from the Almagest which does not include any illustrations. Star Catalogue The book includes a comprehensive catalogue of the individual stars, modified and extended from that of the Almagest, and including revised star magnitude values. Influence The work was highly influential and survives in numerous manuscripts and translations. The oldest manuscript,