RT Journal Article SR Electronic T1 Coal workers’ pneumoconiosis with progressive massive fibrosis JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP E878 OP E878 DO 10.1503/cmaj.111586 VO 184 IS 16 A1 Justin Cheng-Ta Yang A1 Kao-Lang Liu YR 2012 UL http://www.cmaj.ca/content/184/16/E878.abstract