Respected Sir/Madam, One of our scientist is in need of following paper(s), kindly, provide the soft copy of the same, provided you have in your collection(s). 1. D. P. Blair and P. H. Sydenham, “Phase sensitive detection as a means to recover signals buried in noise,” J. Phys. E, Sci. Instrum., vol. 8, no. 8, pp. 621–627, Aug. 1975. 2. E. D. Morris and H. S. Johnston, “Digital phase sensitive detector,” Rev. Sci. Instrum., vol. 39, no. 4, pp. 620–621, Apr. 1968. 3. G. D. Renkes, L. R. Thorne, and W. D. Gwinn, “Digital modulator and synchronous demodulator system: An alternative to the analog phase detector,” Rev. Sci. Instrum., vol. 49, no. 7, pp. 994–1000, Jul. 1978. 4. P. Brobst and A. Jaquier, “Multiple-channel digital lock-in amplifier with PPM resolution,” Rev. Sci. Instrum., vol. 65, no. 3, pp. 747–750, Mar. 1994. 5. F. Barone, E. Calloni, L. DiFiore, A. Grado, L. Milano, and G. Russo, “High-performance modular digital lock-in amplifier,” Rev. Sci. Instrum., vol. 66, no. 6, pp. 3697–3702, Jun. 1995. 6. Global Convergence of QR algorithm. Proceedings of IFIP Congress, 1968 : 130-133(James Hardy Wilkinson) Shelley Jamwal Library Officer 'C' Space Applications Centre/ISRO -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.