Pietarinen, Ahti-Veikko. “Signs Systematically Studied: Invitation to Peirce’s Theory”. Sign Systems Studies 43, no. 4 (December 31, 2015): 372–398. Accessed April 20, 2024. https://ojs.utlib.ee/index.php/sss/article/view/SSS.2015.43.4.01.