[Investigation of personal protective equipment against occupational diseases used by welders in Qingdao municipality].
Chun-Sheng
CS
Xu
Guo-Chang
GC
Feng
Yan-Tao
YT
Liu
D006801:Humans; D016272:Occupational Health; D011482:Protective Devices / Q000706:statistics & numerical data*; D014896:Welding