↑(en) H.Y. He, X.L. Wang, Z.H. Zhou, F. Wang, A. Boven, G.H. Shi et R.X. Zhu, « Timing of the Jiufotang Formation (Jehol Group) in Liaoning, northeastern China, and its implications », Geophysical Research Letters, vol. 31, no 13, , p. 1709 (DOI10.1029/2004GL019790, Bibcode2004GeoRL..3112605H)