Trade-unions History 168 Working class 90 Industrial relations 41 Political activity 39 Labor movement 33 Agricultural laborers 25 Politics and government 24 Socialism 20 Labor laws and legislation 19 Collective bargaining 18 Congresses 18 Law and legislation 17 Economic conditions 16 Officials and employees 15 Strikes and lockouts 14 Wages 12 Biography 11 Periodicals 11 Labor unions 10 Syndicalism 10 Bibliography 9 Employees 9 Management 9 Communism 8 Economic aspects 8 Employee participation 8 Handbooks, manuals, etc 8 Social conditions 8 Sources 8