@article{Karczewska:2015,
  author  = "A. Karczewska and P. Rozmej and E. Infeld",
  title   = "Energy invariant for shallow-water waves and the Korteweg-de Vries equation: Doubts about the invariance of energy",
  journal = "Physical Review E",
  volume  = "Vol. 92",
  pages   = "1--15",
  year    = "2015",
}