Be sure to print out your order confirmation with the order number at the end of the ordering process. If you lose your online tickets, you can bring this document with you on the day of your visit and present it to your colleagues at the entrance. Your tickets can be reissued there.
If you have also deleted or lost the order confirmation, you can send us an e-mail to firstname.lastname@example.org. We will be happy to send you the tickets again, if they are still valid.