The prime sources for the study of Manichaeism are the so-called Turfan (Turpan) texts, named after the Dunhuang region where they were found in 1904–5. These include fragments of Mani's long-lost bible and portions of Manichaean literature written in Pahlavi, Saghdian, Old Turkish, and Chinese. Other sources are a collection of documents found in Egypt in 1933 and refutations of Manichaeism by Christian, Islamic, and Zoroastrian polemicists. See also F. C. Burkitt, The Religion of the Manichees (1925); A. V. W. Jackson, Researches in Manichaeism (1932, repr. 1965); S. Runciman, The Medieval Manichees (1947, repr. 1961); S. N. C. Lien, The Religion of Light (1979) and Manichaeism in the Later Roman Empire and Medieval China (1985).