| Verfasser | Häufigkeit |
| Duncan, Elmer H. |
21 |
| Duncan, Hugh Dalziel 1909-1970 |
16 |
| Duncan, Henry 1774-1846 |
12 |
| Duncan, Anthony H. |
7 |
| Duncan, Hal 1971- |
7 |
| Duncan, Marion Herbert |
6 |
| Hall-Duncan, Nancy |
6 |
| Duncan, Charles H. |
5 |
| Duncan, Wilbur Howard |
4 |
| Duncan, H.O |
3 |
| Duncan, James H. |
3 |
| Janssen, Michel 1953- |
3 |
| Berg, Henk de 1963- |
2 |
| Duncan, Helen |
2 |
| Duncan, Henry |
2 |
| Duncan, Marion B. |
2 |
| Duncan, Wilbur H. |
2 |
| Hall, H. Duncan |
2 |
| Large, Duncan |
2 |
| Malcolm, James A. |
2 |