Darriwilian to Katian (Ordovician) Graptolites from Northwest China - Zhang, Yuandong; Goldman, Daniel; Bergström, Stig M.; Finney, Stanley C.; Chen, Xu; Bergström, Stig M.; Chen Xu, Chen; Chen, Xu; Finney, Stanley C.; Goldman, Daniel; Zhang, Yuandong (Elsevier, 2015)