@article{10_4153_CMB_1965_043_1,
     author = {Ostrom, T. G.},
     title = {Derivable {Nets1)}},
     journal = {Canadian mathematical bulletin},
     pages = {601--613},
     year = {1965},
     volume = {8},
     number = {5},
     doi = {10.4153/CMB-1965-043-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1965-043-1/}
}