7. Trade receivables
| in € thousands | 31 Dec 2008 | 31 Dec 2007 |
|---|---|---|
| Trade receivables | 3,440 | 4,166 |
| Allowances for doubtful accounts | -723 | -987 |
| 2,717 | 3,179 |
Receivables result primarily from rental settlements and uncharged payments for investments. Guarantees, cash security deposits and letters of comfort serve as collateral.