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• Eur. Pat., 1989, 147 850; CA, 104, 5651p
• Verspohl, E.J. et al., J. Pharm. Pharmacol., 1990, 42, 230, (pharmacol)
• Wolffenbuttel, B.H.R. et al., Eur. J. Clin. Pharmacol., 1993, 45, 113, (use)
• Pat. Coop. Treaty (WIPO), 1993, Thomae, 93 00 337; CA, 118, 254759q, (synth, isomers)