Rhazes made important medical contributions as a result of his experience working in the hospitals of Rayy and Baghdad. For example, he is credited with writing the earliest detailed account of smallpox and measles: Kitāb al-jadarī wal-ḥaṣba. He also made important discoveries in the areas of obstetrics and ophthalmology. This edition also includes many other medical treatises in Latin, including works by Hippocrates and Galen, and the books of aphorisms by Maimonides (1138–1204) and Mesue the Elder (d. 857), respectively.