“…For nonlinearly self-adjoint FDEs that do not have a Lagrangian in the classical sense, a formal Lagrangian can be introduced and conservation laws are obtained by using modern techniques based on Lie group analysis of FDEs. This approach, proposed for the first time by Lukashchuk in 2015 [41], has been applied to time fractional PDEs [1, 12, 29, 36, 38-41, 47, 51] and more recently to time and space fractional PDEs (see [54,56] and references therein).…”