[1] [BIPM Brochure, The international System of Units (SI) 9th edition 2019](https://www.bipm.org/en/publications/si-brochure/)
[2] [SmartCom Digital System of Units (D-SI) Guide for the use of the metadata-format used in metrology for the easy-to-use, safe, harmonised and unambiguous digital transfer of metrological data](https://doi.org/10.5281/zenodo.3522631)
[2] [SmartCom Digital System of Units (D-SI) Guide for the use of the metadata-format used in metrology for the easy-to-use, safe, harmonised and unambiguous digital transfer of metrological data](https://doi.org/10.5281/zenodo.3816686)
[3] [SmartCom Digital System of Units (D-SI) Outline of the complete metadata model](https://gitlab1.ptb.de/d-ptb/d-si/xsd-d-si/blob/feat-online-guide/wiki/doc/SmartCom_D-SI_v1.3.pdf)