Lipkowski, A. W.; Tam, S. W.; Portoghese, P. S. (1986). „Peptides as receptor selectivity modulators of opiate pharmacophores”. Journal of Medicinal Chemistry. 29 (7): 1222—5. PMID2879914. doi:10.1021/jm00157a018.
Portoghese, P.S.; Sultana, M.; Takemori, A.E. (1988). „Naltrindole, a highly selective and potent non-peptide δ opioid receptor antagonist”. European Journal of Pharmacology. 146 (1): 185—186. PMID2832195. doi:10.1016/0014-2999(88)90502-X.
Lipkowski, A. W.; Tam, S. W.; Portoghese, P. S. (1986). „Peptides as receptor selectivity modulators of opiate pharmacophores”. Journal of Medicinal Chemistry. 29 (7): 1222—5. PMID2879914. doi:10.1021/jm00157a018.
Portoghese, P.S.; Sultana, M.; Takemori, A.E. (1988). „Naltrindole, a highly selective and potent non-peptide δ opioid receptor antagonist”. European Journal of Pharmacology. 146 (1): 185—186. PMID2832195. doi:10.1016/0014-2999(88)90502-X.