Occurrence and influencing factors of recurrent respiratory tract infection in children aged 3~6 years in Pinggu District of Beijing
LIU Wei-hong;XU Wen-jie;ZHANG Hui-na;LIU Guo-zhong;ZHENG Jun;DING Dan-dan;HU An-ning;LI Ping
Journal of Capital Medical University . 2011, (3): 431 -435 .