8CH. Perelman and L. Olbrechts Tyteca. The New Rhetoric : A Treatise on Argumentation, London : University of Notre Dame Press, 1969, p65.
9CH. Perelman. The New Rhetoric and the Humanities : Essays on Rhetoric and Its Applications. Dordrecht, Holland ; Boston : D. Reidel Pub. Co. , 1979. pp130-131.
10Aulis Aarnio. The rational as reasonable, a treatise on legal justification. D. reidel publishing company, 1987. p202-203.