Case Control Study
Copyright ©The Author(s) 2020.
World J Gastrointest Oncol. Mar 15, 2020; 12(3): 289-300
Published online Mar 15, 2020. doi: 10.4251/wjgo.v12.i3.289
Figure 1
Figure 1 Location map of three selected cities in Shaanxi province, China.