1. https://www.ireb.org/de
2. https://re-buch.de/en/re-buch/re-fundamentals-principles-and-techniques/english-2nd-edition
3. https://www.volere.org/
4. https://ieeexplore.ieee.org/document/8559686 - 29148-2018 - ISO/IEC/IEEE International Standard - Systems and software engineering -- Life cycle processes -- Requirements engineering
5. https://www.sophist.de/: “Standardized document structures such as Volere, the V-model XT or the Standard IEEE 29148 structure have proven themselves particularly successful. SOPHIST additionally relies on the SOPHIST IVENA- and DOHA-Standardized Document Structures.
6. https://arxiv.org/abs/1611.10024