Normal-mode analysis for scalar fields in BTZ black-hole background Sayan K. Chakrabarti, Pulak Ranjan Giri and Kumar S. Gupta Eur. Phys. J. C, 60 2 (2009) 169-173 Published online: 04 February 2009 DOI: 10.1140/epjc/s10052-009-0870-0