Gerard J. Chang Wen-Tsai Ke David Kuo Daphne Der-Fen Liu Roger K. Yeh On <i>L</i>(<i>d</i>, 1)-labelings of graphs. 57-66 2000 220 Discrete Mathematics 1-3 http://dx.doi.org/10.1016/S0012-365X(99)00400-8 db/journals/dm/dm220.html#ChangKKLY00