ß-olded crystal structures of two dipeptides deriving from the L-PRO-L-CYS sequence Virginie Pichon-Pesme, André Aubry and Michel Marraud J. Chim. Phys., 86 (1989) 1181-1193 Published online: 29 May 2017 DOI: 10.1051/jcp/19898601181