Chinese Turkistan and Kansu from surveys made during the explorations of Aurel Stein, 1900-01, 1906-08, 1913-15.
Stein, Marc Aurel,Sir K.C.I.E.
Dehra Dun : Survey of India,
1918-1922.
Vol. 4 of: Innermost Asia. By Aurel Stein.