1. Huff;Huff;Bioorg. Med. Chem.,1999
2. Daluga S.M.; European Patent No. 0,434,450; Dec. 12, 1990
3. Ippen. Joachim et al.; D.B. Patent No. 3,836,161 A1; Nov. 24, 1988; Bayer AG, 5090 Leverkusen, DE
4. Albers-Schonberg G., Wallick H., Ormond R.E., Miller Thomas W., Burg Richard W.; US Patent No. 4,310,519; Jan. 12, 1982; Assigned to Merck and Co., Inc. (Rahway, NJ)
5. Craig D.A., Forrey C.C., Gluchovski Ch., Branchek T.A.; US Patent No. 5,610,174; March 11, 1997; Assigned to Synaptic Pharmaceutical Corporation (Paramus, NJ)