National Socialism, the German variant of twentieth century fascism whose precepts were laid out in Adolf Hitler's Mein Kampf, classified inhabitants of the ideal nation into three main hierarchical categories, each of which had different rights and duties in relation to the state: citizens, subjects, and aliens. The first category, citizens, were to possess full civic rights and responsibilities. Citizenship would be conferred only on those males of pure racial stock who had completed military service, and could be revoked at any time by the state. Only women who worked independently or who married a citizen could obtain citizenship for themselves. The second category, subjects, referred to all others who were born within the nation's boundaries who did not fit the racial criteria for citizenship. Subjects would have no voting rights, could not hold any position within the state, and possessed none of the other rights and civic responsibilities conferred on citizens. The final category, aliens, referred to those who were citizens of another state, who also had no rights: