. 2021 Mar 5;18(5):2644. doi: 10.3390/ijerph18052644
© 2021 by the authors.
Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Figure 4.
The cluster graph of keyword co word analysis.