1C4S:
reference: Chondroitin 4-sulfate: the structure of a sulfated glycosaminoglycan., Winter WT, Arnott S, Isaac DH, Atkins ED, J Mol Biol 1978 Oct 15;125(1):1-19. PMID: 712855

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).