Industrial relations Labor unions 84 History 78 Collective bargaining 69 Working class 62 Personnel management 54 Congresses 52 Management 52 Employee participation 49 Labor laws and legislation 45 Case studies 44 Trade-unions 41 Industrial management 32 Labor economics 31 Labor policy 30 Research 28 Industrial sociology 27 Economic conditions 20 Periodicals 17 Strikes and lockouts 17 International business enterprises 16 Labor supply 16 Arbitration, Industrial 15 Employees 15 Industries 15 Social aspects 15 Study and teaching 14 Labor 13 Bibliography 12 Labor market 12