[Occurrence and etiology of periodontal diseases in 8-18 yr. old children in the town of Pernik, Bulgaria].
D003753:Dental Health Surveys; D010510:Periodontal Diseases / Q000453:epidemiology
Vŭrkhu zaboliaemostta i niakoi etiologichni momenti na parodontopatiite vsred uchenitsi (8-18g.) ot gr. Pernik