@misc{hagner_the_economic_2003, 
author={Hagner, C.},
title={The Economic Productivity at the German Coast},
year={2003},
howpublished = {GKSS report},
note = {Online available at: \url{} (DOI). Hagner, C.: The Economic Productivity at the German Coast. GKSS 2003-14. 2003.}}