RT Journal T1 Epidemiological studies of women under age 30 infected with human papillomavirus A1 Zhihua LIU MD, Qing LI BM, Weihong LI BM, PB Front. Med. FD 2009-12-05 YR 2009 JF Frontiers of Medicine JO Front. Med. VO 3 IS 4 SP 459 DO 10.1007/s11684-009-0084-8 K1 cervical cancer; human papilloma virus; cervical intraepithelial neoplasia LK {https://academic.hep.com.cn/fmd/EN/article/article_10099.shtml}