Comparison of primary cytology, primary HPV testing and co-testing as cervical cancer screening for Chinese women: a population-based screening cohort oleh Xiangxian Feng, Xun Zhang, You-Lin Qiao, Qin-Jing Pan, Shaokai Zhang, Zhi-Fang Li, Xin-Hua Jia, Xun-Wen Zou, Yue-Qing Hao, Xi-Bin Sun