@misc{callies_a_multigrid_1989, 
author={Callies, U., Eppel, D. P.},
title={A multigrid approach to an optimization problem from meteorology},
year={1989},
howpublished = {conference lecture: Copper Mountain, CO (USA);},
note = {Callies, U.; Eppel, D.: A multigrid approach to an optimization problem from meteorology. Fourth Copper Mountain Conference on Multigrid Methods. Copper Mountain, CO (USA), 1989.}}