This is a survey paper on the second largest eigenvalue λ₂ of the adjacency matrix of a graph. Among the topics presented are the graphs with small λ₂, bounds for λ₂, algebraic connectivity, graphs ...

Xue Ding, Tiefeng Jiang, SPECTRAL DISTRIBUTIONS OF ADJACENCY AND LAPLACIAN MATRICES OF RANDOM GRAPHS, The Annals of Applied Probability, Vol. 20, No. 6 (December 2010), pp. 2086-2117 ...