. 2015 Apr 27;36(3):e86–e92. doi: 10.1097/AUD.0000000000000129
Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved.
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Table 1.
Background data for the three groups of railway workers
