1. Aldrich JV, Vigil-Cruz SC. Narcotic analgesics. In: Abraham DJ, ed. Burger’s Medicinal Chemistry and Drug Discovery. Vol 6. New York, NY: John Wiley & Sons; 2003:329-481.
2. Friderichs E. Opioids. In: Buschmann H, Christoph T, Friderichs E, Maul C, Sundermann B, eds. Analgesics, From Chemistry and Pharmacology to Clinical Application. Weinheim, Germany: Wiley-VCH; 2002:127-150.
3. Rapaka RS, Porreca F. Development of delta opioid peptides as nonaddicting analgesics. Pharm Res. 1991;8:1-8.
4. Traynor JR, Elliott J. δ-Opioid receptor subtypes and cross-talk with µ-receptors. Trends Pharmacol Sci. 1993;14:84-86.
5. Rothman RB, Holaday JW, Porreca F. Allosteric coupling among opioid receptors: evidence for an opioid receptor complex. In: Herz A, Akil H, Simon EJ, eds. Handbook of Experimental Pharmacology: Opioids I. Vol 104. Berlin, Germany: Springer-Verlag; 1993:217-237.