@ARTICLE{BHHP,
  author = {Berglund, Nils and Hansen, Alex and Hauge, Eivind H. and Piasecki,
	Jaroslaw},
  title = {Can a local repulsive potential trap an electron?},
  journal = {Phys.\ Rev.\ Letters},
  year = {1996},
  volume = {77},
  pages = {2149--2153}
}