article by Pasquale Migliozzi et al published November 2000 in Physics Letters B

article published in 1993

article by Giovanni De Lellis et al published October 2004 in Physics Reports

scientific article published on 01 July 1996

scientific article published on 01 March 1995

scientific article published on 01 April 1995

scientific article published in January 2000

article published in 2002

scientific article published on 01 April 1996

article published in 1995