Source: https://www.coursum3.org/itic/?wpdf_download_file=/home/ichigo1vs/www8/wp-content/uploads/cours/ITIC/Sciences%20du%20Langage%20parcours%20Sciences%20du%20langage/l1%20science%20du%20language/linguistique%20g%C3%A9n%C3%A9rale/Chapitre%203%20-%20Ferdinnand%20de%20Saussure%20et%20le%20cours%20de%20linguistique%20g%C3%A9n%C3%A9rale.pdf