1. Comité Consultatif des Unités (2016) Draft 2016b of the 9th edition of the SI Brochure (2016b) http://www.bipm.org/en/measurement-units/new-si/#communication . Accessed 31 Jul 2017
2. Comité International des Poids et Measures (CIPM) (2016) (CI 2005). Free downloading from http://www.bipm.org/en/committees/cipm/meeting/105.html . Accessed 31 Jul 2017
3. Metre Convention. Free downloading from http://www.bipm.org/en/worldwide-metrology/metre-convention/ , http://www.bipm.org/en/measurement-units/ . Accessed 31 Jul 2017
4. Bureau International des Poids et Mesures (2006) Le Système International d’Unités (SI), 8th edn. BIPM, Sèvres. Free downloading from http://www.bipm.org/en/publications/si-brochure/ . Accessed 31 Jul 2017
5. Mills IM, Mohr PJ, Quinn TJ, Taylor BN, Williams ER (2006) Redefinition of the kilogram, ampere, kelvin and mole: a proposed approach to implementing CIPM recommendation 1 (CI-2005). Metrologia 43:227–246