1. Department of Urology and Pediatric Urology, Hospital Viersen , Viersen, Germany
2. Department of Urology, Hospital Ibbenbüren , Ibbenbüren, Germany
3. Department of Urology, Hospital Osnabrück , Osnabrück, Germany
4. Private Medical Statistics , Berlin, Germany
5. St. Elizabeth Boardman Family Medicine , Boardman, OH, USA
6. Department of Urology and Pediatric Urology, University Hospital RWTH Aachen , Aachen, Germany