MATURANA R., Humberto - VARELA, Francisco J. Autopoiesis and cognition : the realization of the living. Dordrecht : D. Reidel, c1980. XXX, 141 s. Boston studies in the philosophy of science ; Vol. 42. Available on Internet: <http://www.dandelon.com/servlet/download/attachments/dandelon/ids/AT00120B2.pdf> ISBN 90-277-1016-3.