@article{WindtGrueningerNunneretal.2001,
  author    = {M. Windt and M. Gr{\"u}ninger 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     = {Observation of Two-Magnon Bound States in the Two-Leg Ladders of(Ca,La)14Cu24O41},
  journal   = {Physical Review Letters},
  volume    = {87},
  number    = {12},
  pages     = {127002},
  doi       = {10.1103/physrevlett.87.127002},
  year      = {2001},
}