Evidence for pion absorption on four nucleonsB. Rzehorz, G. Backenstoss, M. Džemidžić, M. Furić, A. Hoffart, T. Petković, H. Ullrich, H. J. Weyer, D. Weiser and M. WildiEurophys. Lett., 34 2 (1996) 103-108DOI: https://doi.org/10.1209/epl/i1996-00423-y