scholarly article by Gillian Hurst published in June 1967

article published in 1964

article published on 1969

scientific article published on January 1961

scientific article published on January 1962

scientific article published on January 1964

scientific article published on January 1965

scientific article published on January 1966

scientific article published on January 1967

scientific article published on January 1968

scientific article published on January 1969

scientific article published on January 1970

article published in 1970