| 1 | air force historical research | | | | | | | 4 | 1.32% |
| 2 | | | | | | | | 4 | 1.32% |
| 3 | force historical research agency | | | | | | | 4 | 1.32% |
| 4 | the air force historical | | | | | | | 3 | 0.99% |
| 5 | the united states air | | | | | | | 2 | 0.66% |
| 6 | united states air force | | | | | | | 2 | 0.66% |
| 7 | air force history index | | | | | | | 1 | 0.33% |
| 8 | force accomplish its missions | | | | | | | 1 | 0.33% |
| 9 | histories beyond that support | | | | | | | 1 | 0.33% |
| 10 | beyond that support provided | | | | | | | 1 | 0.33% |
| 11 | that support provided by | | | | | | | 1 | 0.33% |
| 12 | support provided by afhra | | | | | | | 1 | 0.33% |
| 13 | provided by afhra regularly | | | | | | | 1 | 0.33% |
| 14 | by afhra regularly helps | | | | | | | 1 | 0.33% |
| 15 | todays air force accomplish | | | | | | | 1 | 0.33% |
| 16 | air force accomplish its | | | | | | | 1 | 0.33% |
| 17 | its missions and operations | | | | | | | 1 | 0.33% |
| 18 | accomplish its missions and | | | | | | | 1 | 0.33% |
| 19 | and in volumes of | | | | | | | 1 | 0.33% |
| 20 | missions and operations afhra | | | | | | | 1 | 0.33% |
| 21 | and operations afhra also | | | | | | | 1 | 0.33% |
| 22 | commemorates the individuals and | | | | | | | 1 | 0.33% |
| 23 | the individuals and military | | | | | | | 1 | 0.33% |
| 24 | individuals and military units | | | | | | | 1 | 0.33% |
| 25 | and military units that | | | | | | | 1 | 0.33% |
| 26 | military units that in | | | | | | | 1 | 0.33% |
| 27 | units that in some | | | | | | | 1 | 0.33% |
| 28 | that in some cases | | | | | | | 1 | 0.33% |
| 29 | were called upon to | | | | | | | 1 | 0.33% |
| 30 | called upon to achieve | | | | | | | 1 | 0.33% |
| 31 | upon to achieve the | | | | | | | 1 | 0.33% |
| 32 | to achieve the impossible | | | | | | | 1 | 0.33% |
| 33 | in volumes of oral | | | | | | | 1 | 0.33% |
| 34 | historical records and in | | | | | | | 1 | 0.33% |
| 35 | records and in volumes | | | | | | | 1 | 0.33% |
| 36 | strategic value of documenting | | | | | | | 1 | 0.33% |
| 37 | preserves the important history | | | | | | | 1 | 0.33% |
| 38 | the important history of | | | | | | | 1 | 0.33% |
| 39 | important history of the | | | | | | | 1 | 0.33% |
| 40 | history of the united | | | | | | | 1 | 0.33% |