Cutpoints, lobes and the spectra of graphs Grone, Robert; Merris, Russell — 1988 Portugaliae mathematica
Algebraic connectivity of trees Robert Grone; Russell Merris — 1987 Czechoslovak Mathematical Journal
Spectral radius and seminorms in finite-dimensional algebras. II Robert Grone; Peter D. Johnson, Jr. — 1982 Colloquium Mathematicae