Lee, Ji-Ung; Meyer, Christian M.; Schwan, Erik. Manipulating the difficulty of C-Tests. (2019-07). Creative Commons Attribution 4.0. 409-06 Informationssysteme, Prozess- und Wissensmanagement, 004. Technical University of Darmstadt. https://tudatalib.ulb.tu-darmstadt.de/handle/tudatalib/2704