Subject
United States Politics and government
1,306
United States History
1,141
United States Foreign relations
818
Automobiles Motors Exhaust gas
419
Presidents
395
Air Pollution
375
Air quality management
368
United States Race relations
325
United States Civilization
306
Air quality Standards
218
Academic achievement
205
Educational surveys
200
Air Pollution Standards
199
Vocational education
192
Student aid
189
Air Pollution Measurement
187
Automobiles Fuel consumption
181
History
181
Renewable energy sources
177
Water quality management
173
Legislators
162
United States Social conditions
160
United States History Campaigns
159
Hazardous waste site remediation
158
Student loans
156
Auditing
154
Educational evaluation
152
Presidents Election
149
Federal aid to education
148
Greenhouse gas mitigation
146
United States Social life and customs
146
United States
144
Educational tests and measurements
136
Environmental policy
136
Teachers Training of
130
Education and state
129
Education Parent participation
127
Air Pollution Law and legislation
126
Education, Bilingual
126
Generals
126
Statesmen
123
Education
122
Adult education
121
Transportation Environmental aspects
118
African Americans
115
Energy policy
113
Water Pollution
111
Environmental protection
106
Mathematics Study and teaching
106
Children with disabilities Education
98
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