Modern scholars seeking to understand the history of the Hebrew Bible use a range of sources, in addition to the Masoretic Text. These sources include early Greek (Septuagint) and Syriac (Peshitta) translations, the Samaritan Pentateuch, the Dead Sea Scrolls and quotations from rabbinic manuscripts. Many of these sources may be older than the Masoretic Text and often differ from it. These differences have given rise to the theory that yet another text, an Urtext of the Hebrew Bible, once existed and is the source of the versions extant today. However, such an Urtext has never been found, and which of the three commonly known versions (Septuagint, Masoretic Text, Samaritan Pentateuch) is closest to the Urtext is not fully determined.