Observation of the semileptonic decays D 0 → K S 0 π − π 0 e + ν e $$ D^0→ K_{S}^0π^{-}{π}^0{e}^{+}{ν}_{e} $$ and D + → K S 0 π + π − e + ν e $$ D^{+}→ K_{S}^0π^{+}{π}^{-}{e}^{+}{ν}_{e} $$ - The BESIII collaboration; M. Ablikim; M. N. Achasov; P. Adlarson; X. C. Ai; R. Aliberti; A. Amoroso; M. R. An; Q. An; Y. Bai; O. Bakina; I. Balossino; et al. (Journal of High Energy Physics, 2024)