Planck constant

https://doi.org/10.1351/goldbook.P04685
Universal fundamental physical constant \(h = 6.626\ 06896(33)\times 10^{-34}\ \text{J}\ \text{s}\), or \(\mathrm{\hslash} = \frac{h}{2\ \pi }=1.054\ 571\ 628(53)\times 10^{-34}\ \text{J}\ \text{s}\). The latter is used as @A00504@ of action.
Source:
CODATA Bull., 1986, 63, 1. [Terms] [Book]