Heibig, Arnaud, and Liviu Iulian Iulian Palade. “On the Existence of Solutions to the Fractional Derivative Equations d(alpha)u Dt(alpha)+Au = F, of Relevance to Diffusion in Complex Systems”. Nonlinear Analysis: Modelling and Control, vol. 17, no. 2, Apr. 2012, pp. 153-68, https://doi.org/10.15388/NA.17.2.14065.