Source: https://www.researchgate.net/profile/Jean-Michel_Albaret/publication/309493328_Le_developpement_du_dessin_des_praxies_constructives_et_de_l'ecriture/links/58138c2308aeb720f6829177/Le-developpement-du-dessin-des-praxies-constructives-et-de-lecriture.pdf