A good beginning: 20 years in the hospitals.
D001741:Black or African American; D000488:Allied Health Personnel; D049673:History, 20th Century; D007750:Labor Unions / Q000266:history*; D010564:Personnel, Hospital; D012456:Salaries and Fringe Benefits; D013317:Strikes, Employee; D014481:United States; D014933:Women's Rights