Chemical Synthesis, protom nmr. Parameters, hydrogen- and calcium-ion complexation of L-γ-carboxyglutamyl-L-γ-carboxyglutamic acid and D-γ-carboxyglutamyl-L-leucine - Märki, W; Oppliger, M; Schwyzer, R (Helv. Chim. Acta, 1977)