A. Ferrer, B. Bouquet, B. d'Almagne, C. Dang Vu, A. Jacholkowski, et al.. Backward enhancement in the A$_1$ region and A$_2$ production in the reaction $\pi^-p \rightarrow p_f\pi^+\pi^-\pi^-$ at 9 and 12 GeV/c. Physics Letters B, Elsevier, 1978, 74, pp.287-291. ⟨in2p3-00021199⟩