Quizá quiso decir: Población ; 50/2008. Población ; 50/2008. Catastrophe Modeling, 0924-5014 ; 25 Texts in Applied Mathematics, 0939-2475 ; 50 Huebner International Series on Risk, Insurance and Economic Security, 0924-5014 ; 26 Mathematical Concepts and Methods in Science and Engineering ; 50 Fuel Cells and Hydrogen Energy, 1931-5058 Fuel Cells and Hydrogen Energy, 1931-5058 Advances in Information Security, 1568-2633 ; 50 Springer Series on Atomic, Optical, and Plasma Physics, 1615-5653 ; 50 Progress in Mathematical Physics ; 50 Human-Computer Interaction Series, 1571-5035 Human-Computer Interaction Series, 1571-5035 Human-Computer Interaction Series, 1571-5035 Human-Computer Interaction Series, 1571-5035 Human-Computer Interaction Series, 1571-5035 Human-Computer Interaction Series, 1571-5035 Human-Computer Interaction Series, 1571-5035 ; 7 Human-Computer Interaction Series, 1571-5035 ; 3 Water Science and Technology Library, 0921-092X ; 50