CHOBANOV, I. INTRODUCTION TO AN ALGEBRAIC THEORY OF ARROWS, II. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 82, n. 1, p. 63–117, 1991. Disponível em: https://ftl5.uni-sofia.bg/index.php/fmi/article/view/523. Acesso em: 5 dec. 2024.