Higashikawa Y, Suzuki S. Studies on 1-(2-phenethyl)-4-(N-propionylanilino)piperidine (fentanyl) and its related compounds. VI. Structure-analgesic activity relationship for fentanyl, methyl-substituted fentanyls and other analogues. Forensic Toxicology. June 2008, 26 (1): 1–5. S2CID 22092512. doi:10.1007/s11419-007-0039-1.
Alburges ME, Hanson GR, Gibb JW, Sakashita CO, Rollins DE. Fentanyl receptor assay. II. Utilization of a radioreceptor assay for the analysis of fentanyl analogs in urine. Journal of Analytical Toxicology. 1992, 16 (1): 36–41. PMID 1322477. doi:10.1093/jat/16.1.36.
Woods J, Medzihradsky F, Smith C, Winger G, Gmerek D. Evaluation of new compounds for opioid activity: 1987 annual report. NIDA Research Monograph. 1988, 81: 543–590. PMID 3136388.
Aceto M, Bowman E, Harris L, May E. Dependence studies of new compounds in the rhesus monkey, rat, and mouse, 1987. NIDA Research Monograph. 1988, 81: 485–542. PMID 3136386.
Brine GA, Boldt KG, Huang PT, Sawyer DK, Carroll FI. Carbon-13 nuclear magnetic resonance spectra of fentanyl analogs. Journal of Heterocyclic Chemistry. 2009, 26 (3): 677–686. doi:10.1002/jhet.5570260329.