@misc{siegmund_prediction_of_1999, 
author={Siegmund, T.,Brocks, W.},
title={Prediction of the work of separation and implications to modeling},
year={1999},
howpublished = {journal article,GKSS report},
note = {Online available at: \url{} (DOI). Siegmund, T.; Brocks, W.: Prediction of the work of separation and implications to modeling. International Journal of Fracture. 1999. vol. 99, 97-116.}}