@article{JAC_1999__10_1_a5,
     author = {Brouwer, A.E. and Koolen, J.H.},
     title = {The distance-regular graphs of valency four},
     journal = {Journal of Algebraic Combinatorics},
     pages = {5--24},
     publisher = {mathdoc},
     volume = {10},
     number = {1},
     year = {1999},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JAC_1999__10_1_a5/}
}