D. Seebach, M. Albert, P. I. Arvidsson, M. Rueping, and J. V. Schreiber, “From the Biopolymer PHB to Biological Investigations of Unnatural β- and γ-Peptides”, Chimia, vol. 55, no. 4, p. 345, Apr. 2001, doi: 10.2533/chimia.2001.345.