Perfectly matchable edges in a bipartite graph Consider the following problem:

Given a bipartite graph $G = (V, E)$, an unmatched edge is one that does not appear in any perfect matching. Design an algorithm to find all unmatched edges. (assume |V| = n and |E| = m)

There is an $O(m + T(m, n))$ algorithm to solve this problem [1, Web exercise 36]. Where $T(m, n)$ is the time complexity of the best algorithm for finding perfect matching in a bipartite graph $G$. I want to get a reference to the research paper/work where the algorithm was proposed, for citation.

[1] http://algs4.cs.princeton.edu/42directed/
It's a consequence of Dulmage-Mendelsohn decompositions.