  We prove the edge and bulk universality of random Hermitian matrices with
equi-spaced external source. One feature of our method is that we use neither a
Christoffel-Darboux type formula, nor a double-contour formula, which are
standard methods to prove universality results for exactly solvable models.
This matrix model is an example of a biorthogonal ensemble, which is a special
kind of determinantal point process whose kernel generally does not have a
Christoffel-Darboux type formula or double-contour representation. Our methods
may showcase how to handle universality problems for biorthogonal ensembles in
general.
