Freshwater Fossil Pearls from the Nihewan Basin, Early Early Pleistocene Li, Su-Ping ; Yao, Pei-Yi ; Li, Jin-Feng ; Ferguson, David Kay ; Min, Long-Rui ; Chi, Zhen-Qing ; Wang, Yong ; Yao, Jian-Xin ; Sha, Jin-Geng Abstract Publication: PLoS ONE Pub Date: October 2016 DOI: 10.1371/journal.pone.0164083 Bibcode: 2016PLoSO..1164083L