Institution: | 1. Departamento de Matemáticas Aplicadas y Sistemas, Universidad Autónoma Metropolitana-Cuajimalpa, Vasco de Quiroga 4871, 05348 Mexico City, Mexico;2. Department of Physics, Chemistry and Mathematics, Alabama A&M University, Normal, AL 35762, USA;3. Department of Mathematics and Statistics, Tshwane University of Technology, Pretoria 0008, South Africa |