@inbook{pfenning_schrmann_1999, title={System Description: Twelf — A Meta-Logical Framework for Deductive Systems}, ISBN={9783540486602}, ISSN={0302-9743}, url={http://dx.doi.org/10.1007/3-540-48660-7_14}, DOI={10.1007/3-540-48660-7_14}, booktitle={Automated Deduction — CADE-16}, publisher={Springer Berlin Heidelberg}, author={Pfenning, Frank and Schürmann, Carsten}, year={1999}, pages={202–206} }