Your referees will receive a link to an online application system where to upload their letters in PDF format (not larger than 2 MB). The file can only be uploaded once. A successful upload will be immediately confirmed on screen. If they fail to upload their file for the first time, or if there is no onscreen confirmation, they should contact application[at]geas.fu-berlin.de to await further instructions.
If any other technical mishap occurs, they can also contact the above email address.