artículo científico publicado el 1 de abril de 1991

artículo científico publicado en 1987

field study published in 1978

field study published in 1972

field study published in 1974

field study published in 1975

field study published in 1975

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field study published in 1975

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field study published in 1977

field study published in 1978

field study published in 1979

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field study published in 1972

field study published in 1976

field study published in 1977

field study published in 1977

field study published in 1978

field study published in 1979

field study published in 1979

field study published in 1979

field study published in 1979

field study published in 1975

field study published in 1976

field study published in 1977

field study published in 1977

field study published in 1978

field study published in 1979

field study published in 1978

field study published in 1979

field study published in 1979

field study published in 1982

field study published in 1981

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field study published in 1983

field study published in 1982

field study published in 1982

field study published in 1982

field study published in 1982

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field study published in 1982

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field study published in 1982

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field study published in 1987

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field study published in 1987

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field study published in 1973

field study published in 1972

field study published in 1981

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field study published in 1981

field study published in 1980

field study published in 1977

field study published in 1977

field study published in 1978

field study published in 1981

field study published in 1981

field study published in 1981

field study published in 1981