@article{JIS_2000__3_2_a0,
     author = {Royle,  Gordon F.},
     title = {Counting set covers and split graphs},
     journal = {Journal of integer sequences},
     year = {2000},
     volume = {3},
     number = {2},
     zbl = {0953.05033},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2000__3_2_a0/}
}