@article{JIS_2004__7_3_a2,
     author = {McKay, Brendan D. and Oggier, Fr\'ed\'erique E. and Royle, Gordon F. and Sloane, N.J.A. and Wanless, Ian M. and Wilf, Herbert S.},
     title = {Acyclic digraphs and eigenvalues of $(0,1)$-matrices},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {7},
     number = {3},
     year = {2004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2004__7_3_a2/}
}