$\mathbf{A} = \frac{\mu_0}{4\pi}\int \frac{\mathbf{J}}{r} d\tau$

$\nabla^2 \mathbf{A} = -\mu_0 \mathbf{J}$

$\mathbf{B} = \frac{\mu_0}{4\pi}\int \frac{\mathbf{J} \times \hat{\mathbf{r}}}{r^2} d\tau$

$\nabla \times \mathbf{B} = \mu_0 \mathbf{J}$

$\mathbf{B} = \nabla \times \mathbf{A}$

(Rarely Used)