Topic
- Finance97
- Emigration and immigration96
- Impeachment96
- Labor union members93
- Medical care90
- Political activity90
- Study and teaching90
- Vietnam War, 1961-197590
- Knowledge and learning89
- Education87
- Political aspects86
- Students86
- Research85
- Influence84
- Strikes and lockouts84
- Popular music81
- Prevention81
- Economic development79
- Interpersonal relations79
- Arab-Israeli conflict78