Nanqiu Town in Huanxian County, Gansu Province (106.713, 36.916, Middle Ordovician)
Ge, M.Y., Zheng Z.C., Li, Y.Z. 1990. Research of Ordovician and Silurian graptolites and graptolite bearing strata from Ningxia and the neighbouring districts. Nanjing, Nanjing University Press, 1–190.