1. Apple and Goldman sachs launch their credit card. The Economist. ISSN 0013-0613.
2. Schneider, Frank, and Sabrina Weber-Papen. 1996. Psychiatrie, Psychosomatik und Psychotherapie ...in 5 Tagen, 85. Heidelberg: Springer. ISBN 978-3-540-89049-2.
3. United States of America, Appellee v. Microsoft Corporation, Appellant, 253 F.3d 34 (D.C. Cir. 2001). https://law.justia.com/cases/federal/appellate-courts/F3/253/34/576095/, 2001.
4. Global Internet Usage. Wikipedia, November 2018. Page Version ID: 870834776.
5. OpenSchufa: The first results. https://okfn.de/blog/2018/11/openschufa-first-results/, 2018.