|Bureau International des poids et mesures (Hrsg.) (1889 / 2019). The International System of Units (SI). Sèvres Cedex: BIPM. S.205.|
In 1889 the 1st CGPM sanctioned the international prototypes for the metre and the kilogram. Together with the astronomical second as the unit of time, these units constituted a three-dimensional mechanical unit system similar to the CGS system, but with the base units metre, kilogram and second, known as the MKS system.