@article{10_4153_CJM_1977_013_6,
     author = {Sherk, F. A. and Pabst, G\"unther},
     title = {Indicator {Sets,} {Reguli,} and a {New} {Class} of {Spreads}},
     journal = {Canadian journal of mathematics},
     pages = {132--154},
     year = {1977},
     volume = {29},
     number = {1},
     doi = {10.4153/CJM-1977-013-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1977-013-6/}
}