@misc{claussen_estimation_of_1990, 
author={Claussen, M.},
title={Estimation of areally-averaged surface fluxes},
year={1990},
howpublished = {conference lecture: Groningen (D);},
note = {Claussen, M.: Estimation of areally-averaged surface fluxes. Colloquium of the Department of Physical Geography, University of Groningen. Groningen (D), 1990.}}