Cologne University Complete Catalogue (KUG): http://kug.ub.uni-koeln.de/
Communication and information system Vocational Education and Training (KIBB) of the Federal Institute for Vocational Education and Training (BIBB): https://www.bibb.de/veroeffentlichungen/de/bwp/show/631
FIS Education: http://www.fachportal-paedagogik.de/fis_bildung/