NS-EN ISO 80000-2:2013 Quantities and units - Part 2: Mathematical signs and symbols to be used in the natural sciences and technology (ISO 80000-2:2009)
2020NS-EN ISO 80000-2:2019 Quantities and units — Part 2: Mathematics (ISO 80000-2:2019, Corrected version 2021-11)
2013NS-EN ISO 80000-2:2013 Quantities and units - Part 2: Mathematical signs and symbols to be used in the natural sciences and technology (ISO 80000-2:2009)