1. The International System of Units (SI Brochure) 9th edn,2019
2. The International System of Units (SI Brochure), appendix 2: practical realizations of the definitions of some important units—mises en pratique 9th edn,2019
3. The International System of Units (SI Brochure), appendix 2: practical realizations of the definitions of some important units—mises en pratique, mise en pratique for the definition of the metre in the SI 9th edn,2019
4. The International System of Units (SI),2009
5. Resolution 1 of the 17th CGPM, definition of the metre,1983