@article{GrueningerWindtNunneretal.2002,
  author    = {Markus Gr{\"u}ninger and Marco Windt and Tamara Nunner and C. Knetter and K. P. Schmidt and G. S. Uhrig and Thilo Kopp and A. Freimuth and U. Ammerahl and B. B{\"u}chner and A. Revcolevschi},
  title     = {Magnetic excitations in two-leg spin 1/2 ladders: experiment and theory},
  journal   = {Journal of Physics and Chemistry of Solids},
  volume    = {63},
  number    = {12},
  pages     = {2167 -- 2173},
  doi       = {10.1016/s0022-3697(02)00251-2},
  year      = {2002},
}