@misc{heerens_delta_5_2001, 
author={Heerens, J., Schoedel, M., Hellmann, D.},
title={Delta 5 and CTOA - Experimental and Numerical Observations},
year={2001},
howpublished = {conference lecture: Geesthacht (D);},
note = {Heerens, J.; Schoedel, M.; Hellmann, D.: Delta 5 and CTOA - Experimental and Numerical Observations. Workshop on the Fundamentals and Applications of the Crack Tip Opening Angle (CTOA). Geesthacht (D), 2001.}}