title: Unusual pulmonary observations and exposure to coal mine dust: a case-control study.
mesh_terms: D000328:Adult; D003032:Coal Mining; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011009:Pneumoconiosis / Q000175:diagnosis / Q000000981:diagnostic imaging*; D011859:Radiography