journal article published in 1991

journal article published in 2005

abstract published in 2000

journal article published in 1997

journal article published in 1987

abstract published in 1998

scientific article published on September 1, 2003

abstract published in 2003

abstract published in 2005

journal article published in 1987

field study published in 1986

scientific article published on December 1, 1981

journal article published in 1989

conference abstract published in 2004