@article{10_4153_CMB_1970_028_2,
     author = {Mullin, R. C. and Nemeth, E.},
     title = {On the {Nonexistence} of {Orthogonal} {Steiner} {Systems} of {Order} 9},
     journal = {Canadian mathematical bulletin},
     pages = {131--134},
     year = {1970},
     volume = {13},
     number = {1},
     doi = {10.4153/CMB-1970-028-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1970-028-2/}
}