Existence of normalized solutions to Choquard equation with general mixed nonlinearities

We study the existence of normalized solutions to the following Choquard equation with F being a Berestycki-Lions type function equation* cases - u+ u= (I_ F (u) ) f (u), in\ RN, \\ ₑ₍|u|²dx=², cases equation* where N 3, >0 is assigned, (0, N), I_ is the Riesz potential, and R is an unknown parameter that appears as a Lagrange multiplier. Here, the general nonlinearity F contains the L²-subcritical and L²-supercritical mixed case, the Hardy-Littlewood-Sobolev lower critical and upper critical cases.