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Regular graphs with four eigenvalues
van Dam, Edwin Robert, (1994)
Bounds on separated pairs of subgraphs, eigenvalues and related polynomials
van Dam, Edwin Robert, (1995)
Interlacing eigenvalues and graphs
Haemers, W.H., (1994)
Spectral Characterizations of Some Distance-Regular Graphs
van Dam, Edwin Robert, (2000)