| Relationships | Role | Relationship Start | Relationship End |
| Deutsche Tiefbohr Ag | Parent | 12/31/1993 | 12/31/1996 |
| Deutsche Tiefbohr Ag | Parent | 12/31/1987 | 12/30/1991 |
| C. Deilmann Ag | Parent | 12/31/1985 | 12/30/1987 |
| Relationships | Role | Relationship Start | Relationship End |
| Deutsche Tiefbohr Ag | Parent | 12/31/1993 | 12/31/1996 |
| Deutsche Tiefbohr Ag | Parent | 12/31/1987 | 12/30/1991 |
| C. Deilmann Ag | Parent | 12/31/1985 | 12/30/1987 |