Quizá quiso decir: Computational Methods in Applied Sciences, 1871-3033 ; 30 Población ; 30/2007. Población ; 30/2007. Recerca ; 30. Población ; 30/2007. Población ; 30/2007. Aldina ; 30. Sepan Cuantos 300 Combinatorial Optimization, 1388-3011 ; 12 Cancer Treatment and Research, 0927-3042 ; 147 Power Electronics and Power Systems, 2196-3185 ; 30 Economics of Science, Technology and Innovation, 1381-0480 ; 30 Combinatorial Optimization, 1388-3011 ; 16 Combinatorial Optimization, 1388-3011 ; 17 Cancer Treatment and Research, 0927-3042 ; 127 Operations Research/Computer Science Interfaces Series, 1387-666X ; 30 Cancer Treatment and Research, 0927-3042 ; 124 Cancer Treatment and Research, 0927-3042 ; 125 Cancer Treatment and Research, 0927-3042 ; 126 Advances in Database Systems, 1386-2944 ; 30