@article{10_37236_91,
     author = {Robert Morris},
     title = {Minimal percolating sets in bootstrap percolation},
     journal = {The electronic journal of combinatorics},
     year = {2009},
     volume = {16},
     number = {1},
     doi = {10.37236/91},
     zbl = {1178.60070},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/91/}
}