Modeling of a Mass-Spring-Damper System by Fractional Derivatives with and without a Singular Kernel. - José Francisco Gómez-Aguilar; Huitzilin Yépez-Martínez; Celia Calderón-Ramón; Ines Cruz-Orduña; Ricardo Fabricio Escobar-Jiménez; Victor Hugo Olivares-Peregrino (Entropy, 2015)