Brouwer, A. E. "Higman-Sims Graph." http://www.win.tue.nl/~aeb/drg/graphs/Higman-Sims.html.Brouwer, A. E. "The Uniqueness of the Strongly Regular Graph of 77 Points." J. Graph Th.7, 455-461, 1983.Brouwer, A. E.; Cohen, A. M.; and Neumaier, A. Distance-Regular Graphs. New York: Springer-Verlag, pp. 163 and 391, 1989.Brouwer, A. E. and Haemers, W. H. "The Gewirtz Graph: An Exercise in the Theory of Graph Spectra." Euro. J. Combin.14, 397-407, 1993.Brouwer, A. E. and van Lint, J. H. "Strongly Regular Graphs and Partial Geometries." In Enumeration and Design: Papers from the conference on combinatorics held at the University of Waterloo, Waterloo, Ont., June 14-July 2, 1982 (Ed. D. M. Jackson and S. A. Vanstone). Toronto, Canada: Academic Press, pp. 85-122, 1984.Brouwer, A. E. and van Maldeghem, H. "The Higman-Sims Graph." §10.31 in Strongly Regular Graphs. Cambridge, England: Cambridge University Press, pp. 303-304, 2022.Conway, J. H. and Sloane, N. J. A. Sphere Packings, Lattices and Groups, 3rd ed. New York: Springer-Verlag, 1999.DistanceRegular.org. "Higman-Sims Graph." http://www.distanceregular.org/graphs/higman-sims.html.Gaucher, A. P. "Leech Lattice." https://cp4space.hatsya.com/2013/09/12/leech-lattice/. Sep. 12, 2013.Gewirtz, A. "Graphs with Maximal Even Girth." Canad. J. Math.21, 915-934, 1969.Goethals, J.-M. and Seidel, J. J. "Strongly Regular Graphs Derived from Combinatorial Designs." Can. J. Math.22, 597-514, 1970.Hafner, P. R. "On the Graphs of Hoffman-Singleton and Higman-Sims." Elec. J. Combin.11, R77, 1-32, 2004.Higman, D. G. and Sims, C. C. "A Simple Group of Order ." Math. Z.105 , 110-113, 1968.Tonchev, V. D. "Binary Codes Derived from the Hoffman-Singleton and Higman-Sims Graphs." IEEE Trans. Info. Th.43, 1021-1025, 1997.van Dam, E. R. and Haemers, W. H. "Spectral Characterizations of Some Distance-Regular Graphs." J. Algebraic Combin.15, 189-202, 2003.