aLicenciatura en Matemáticas, Universidad del Quindío, Quindío, Colombia
bDepartamento de Matematicas, Universidad del Valle, Cali, Colombia
cMathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA
dDepartment of Applied Mathematics, Kyung Hee University, Yongin, Korea
© 2014 Published by Elsevier B.V. on behalf of Korea Centers for Disease Control and Prevention.
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