https://doi.org/10.1351/goldbook.B00693
Atomic fundamental physical constant used as @[email protected] of length: \[a_{0}=\frac{4\ \pi \ \varepsilon_{0}\ \mathrm{\hslash }^{2}}{m_{\text{e}}\ e^{2}}=5.291 \ 772\ 49\ (24)\times 10^{-11}\ \text{m}\] where \(e\) is the @[email protected], \(\mathrm{\hslash}\) is the @[email protected] divided by \(2\ \pi \) and \(m_{\text{e}}\) is the @[email protected]
Source:
CODATA Bull. 1986, 63, 1 [Terms] [Book]