Perkhun L. Р. Studying the workforce in the professional qualification context: the US experience. Statistics of Ukraine, [S. l.], n. 4(79), p. 65–69, 2017. DOI: 10.31767/su.4(79).2017.04.08. Disponível em: https://su-journal.com.ua/index.php/journal/article/view/148. Acesso em: 28 jun. 2026.