Gerd Fricke Michael A. Henning Ortrud Oellermann Henda C. Swart An Algorithm to Find Two Distance Domination Parameters in a Graph. 85-91 1996 68 Discrete Applied Mathematics 1-2 http://dx.doi.org/10.1016/0166-218X(95)00057-X db/journals/dam/dam68.html#FrickeHOS96