The orbital magnetic dipole moment of a particle with mass $m$ and charge $q$ can be shown to be related to the orbital angular momentum through the equation
One of the quantum mechanics textbooks has instead the same equation but with the speed of light in the denominator,
The same book also defined the spin magnetic dipole moment for the electron with a $c$,
where $g$ is the usual Lande factor (~2).
Is the speed of light appearing in those equations just a typo? (but it is not in the book errata)