Brown JH, Jardetzky TS, Gorga JC, Stern LJ, Urban RG, Strominger JL, Wiley DC. Pillars article: three-dimensional structure of the human class II histocompatibility antigen HLA-DR1. Nature. 1993. 364: 33-39. J Immunol. 2015 Jan 01; 194(1):5-11.