During the summer of 1932,Y.S.Chi made a detailed study of thegeology of the Mentoukou (门头溝) and Sanchiatien (三家店) area of Hsishan,or the Sanchiatien Sheet~2 of the Ordnance Map in the scale 1 to 25,000.The
Y. S. CHI & C. H. P'AN.1933. ON THE EXISTENCE OF THE SHUANGTSüAN SERIES AND ITS TRIASSIC FLORA IN HSISHAN OR THE WESTERN HILLS OF PEIPING[J]. Acta Geologica Sinica(),12(0):
