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Ohta, H.; Suzuki, S.; Ogasawara, K., Studies on fentanyl and related compounds. IV. Chromatographic and spectrometric discrimination of fentanyl and its derivatives, J. Anal. Toxicol., 1999, 23, 4, 280-285, https://doi.org/10.1093/jat/23.4.280 . [all data]