Transient bi-fractional diffusion: space-time coupling inducing the coexistence of two fractional diffusionsJian Liu, Yaohui Zhu, Peisong He, Xiaosong Chen and Jing-Dong BaoEur. Phys. J. B, 90 4 (2017) 70DOI: https://doi.org/10.1140/epjb/e2017-80060-5