Observation of B→D(*) π^(+)π^(-)ℓ^(-)ν Decays in e^(+)e^(-) Collisions at the Υ(4S) Resonance. - Lees JP; Poireau V; Tisserand V; Grauges E; Palano A; Eigen G; Stugu B; Brown DN; Kerth LT; Kolomensky YG; Lee MJ; Lynch G; et al. (Physical review letters, 2016)