scientific article published on September 1, 1997

scientific article published in September 2000

scientific article published on December 2003

scientific article (publication date: 1999)

scientific article

scientific article published in January 1991

scientific article published on January 2000

scientific article published on August 1990

scientific article published on November 2002

scientific article published on January 2001

scientific article published on September 1, 1992

scientific article published in September 1993

scientific article published on 01 April 1993