Definition Let $G=U\cup V$ is bipartite graph, where $U$ and $V$ are disjoint sets of size $p$ and $q$, respectively. The complete bipartite graph denoted by $K_{p,q}$ is bipartite graph where every vertex in $U$ is connected to every vertex in $V$.
Background It is known that the eigenvalues of complete bipartite graph $K_{p,q}$ are $\sqrt{pq}$, -$\sqrt{pq}$, and 0 with multiplicity $p+q-2$. (see Theorem 3.4 in [1]).
Question My question: Can this result generalized to regular bipartite graph?
In other words what is the eigenvalues of $d$-regular bipartite graph, where $d\leq p$? (Note that in this case $|U|=|V|=p$ ).
Any help will be useful!