@article{JRAM_1989__398_153149,
     author = {Burkhard K\"ulshammer},
     title = {Blocks, solvable permutation groups, and {Landau's} theorem.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {180--186},
     publisher = {mathdoc},
     volume = {398},
     year = {1989},
     zbl = {0666.20003},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1989__398_153149/}
}