PDB1G1R; Somers WS, Tang J, Shaw GD, Camphausen RT. Insights into the molecular basis of leukocyte tethering and rolling revealed by structures of P- and E-selectin bound to SLe(X) and PSGL-1. Cell. October 2000, 103 (3): 467–79. PMID 11081633. doi:10.1016/S0092-8674(00)00138-0.