1DBB:
reference: Three-dimensional structure of an anti-steroid Fab' and progesterone-Fab' complex., Arevalo JH, Stura EA, Taussig MJ, Wilson IA, J Mol Biol 1993 May 5;231(1):103-18. PMID: 8496956

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