Molecular docking reveals a novel binding site model for fentanyl at the mu-opioid receptor.
Subramanian G, Paterlini MG, Portoghese PS, Ferguson DM, J Med Chem, 2000 Feb 10 - link

Conformational analysis and automated receptor docking of selective arylacetamide-based kappa-opioid agonists.
Subramanian G, Paterlini MG, Larson DL, Portoghese PS, Ferguson DM, J Med Chem, 1998 Nov 19 - link