The change in multiplicity of an eigenvalue of a Hermitian matrix associated with the removal of an edge from its graph. - Charles R. Johnson; Paul R. McMichael (Discret. Math., 2011)

Changes in vertex status and the fundamental decomposition of a tree relative to a multiple (parter) eigenvalue. - Charles R. Johnson; António Leal Duarte; Paul R. McMichael (Discret. Appl. Math., 2017)