@article{XuCaoTianetal.2014,
  author    = {QingHai Xu and Xianyong Cao and Fang Tian and ShengRui Zhang and YueCong Li and ManYue Li and Jie Li and YaoLiang Liu and Jian Liang},
  title     = {Relative pollen productivities of typical steppe species in northern China and their potential in past vegetation reconstruction},
  journal   = {Science China},
  volume    = {57},
  number    = {6},
  pages     = {1254 -- 1266},
  doi       = {10.1007/s11430-013-4738-7},
  year      = {2014},
}