## Wikipedia - Candela (unità di misura) (it) candela, $$\text{cd}$$

https://doi.org/10.1351/goldbook.C00787
The candela, symbol $$\text{cd}$$, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency $$540\times 10^{12}\ \text{Hz}$$, $$K_{cd}$$, to be $$683$$ when expressed in the unit $$\text{lm W}^{-1}$$, which is equal to $$\text{cd sr W}^{-1}$$, or $$\text{cd sr kg}^{-1}\ \text{m}^{-2}\ \text{s}^{3}$$, where the kilogram, metre and second are defined in terms of @P04685@, @S05854-1@ and @S05854-2@.
Source:
BIPM, The International System of Units, SI Brochure, 9th ed. (2019), p. 135 [Terms] [Book]