Hello,
I tried to put down the Persistent Identifier (internet-adress) in the DOI-Field. But it doesn't work.The PID is: https://nbn-resolving.org/urn:nbn:de:0168-ssoar-67412-2 (I checked it - it is O.K.) but the error message is: The DOI you entered seems to be structured incorrectly. Please check it and try again.
Can anyone help? Thanx in advance!