C. Edmund Bosworth, (2002), 'CENTRAL ASIA iv. In the Islamic Period up to the Mongols'Encyclopaedia Iranica "In early Islamic times Persians tended to identify all the lands to the northeast of Khorasan and lying beyond the Oxus with the region of Turan, which in the Šāh-nāma of Ferdowsī is regarded as the land allotted to Ferēdūn’s son Tūr...At the outset, however, those nearby parts of Central Asia with which the Arabs were familiar were often subsumed into the vast and ill-defined province of Khorasan, embracing all lands to the east of Ray, Jebāl, and Fārs." (online)
C. Edmund Bosworth, (2011), 'MĀ WARĀʾ AL-NAHR'Encyclopaedia Iranica " It was defined by the early Arabic historians and geographers as the lands under Muslim control lying to the north of the middle and upper Oxus or Āmu Daryā, in contrast to Iran proper and its eastern province of Khorasan, sometimes called Mā dun al-nahr (lit. “what lies this side of the river”), although from the perspective of Arab historians writing in distant Iraq, the term “Khorasan” might extend to all lands beyond the Oxus, including Khwarazm and Transoxiana." (online)
Sabloff, Paula L.W. (2011). Mapping Mongolia: Situating Mongolia in the World from Geologic Time to the Present. Philadelphia: University of Pennsylvania Museum of Archaeology and Anthropology. стр. 62. ISBN978-1934536186. OCLC794700604.
