@article{SLC_1991_26_a6,
     author = {J. J. Seidel},
     title = {Introduction to {Association} {Schemes}},
     journal = {S\'eminaire lotharingien de combinatoire},
     year = {1991},
     volume = {26},
     url = {http://geodesic.mathdoc.fr/item/SLC_1991_26_a6/}
}