scientific article published in 1966

scientific article published in September 1972

scientific article published in 2001

scientific article published in 1978

scientific article published in 1990

scientific article published in June 1995

scientific article published in January 1976

scientific article published in 1980

scientific article published in January 1976

scientific article published in 1993

scientific article published in 1980

scientific article published in 1983

scientific article published in March 1991

scientific article published in 1996

scholarly article from 'Journal of Combinatorial Theory, Series B' published in 2004

scientific article published on 21 July 2005

scientific article published in September 1994

scientific article published in 1993