scholarly article by John Clark published in January 1994

scientific article published in January 1995

scientific article published in January 1983

scientific article published in January 1984

scientific article published in January 1985

scientific article published in January 1986

scientific article published in January 1987

scientific article published in January 1988

scientific article published on January 1981

scientific article published in January 1982

scientific article published in January 1983