letter . 2021 Aug;50(8):1722–1723. doi: 10.18502/ijph.v50i8.6820
Copyright © 2021 Chen et al. Published by Tehran University of Medical Sciences
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International license (https://creativecommons.org/licenses/by-nc/4.0/). Non-commercial uses of the work are permitted, provided the original work is properly cited.