@book{Walker+2021,
url = {https://doi.org/10.3790/9783428583348},
title = {Die Kosten kostenloser Dienste},
title = {Personenbezogene Daten als neues Zahlungsmittel},
author = {Matthias Walker},
publisher = {Duncker & Humblot},
address = {},
doi = {doi:10.3790/9783428583348},
isbn = {9783428583348},
year = {2021},
lastchecked = {2021}
}