 In his 1922 lectures on atomic theory in Göttingen, Bohr again emphasizes that the correspondence principle holds even for low quantum number transitions. This can particularly be seen in his discussion of the well-known red and green spectral lines of the Balmer series in the visible part of the hydrogen spectrum. The red spectral line (which really is red at a wavelength of around 656 nm) is typically labeled \(\rH_{\alpha}\), and is the result of radiation emitted in the jump from the \(n = 3\) to \(n = 2\) stationary state. The green line (labeled \(\rH_{\beta}\) with a wavelength of around 486 nm) is a result of the electron in a hydrogen atom jumping from the \(n = 4\) to \(n = 2\) stationary state.