"Language Learning and Migration" funded by the German Research Foundation (DFG)
For more information about the project, please see here.
Uebelmesser, Silke, Matthias Huber, and Severin Weingarten (2018). "The German Language Worldwide: a New Data Set on Language Learning". CESifo Economic Studies 64 (1), 103-121. (Link to CESifo Economic Studies)