Kopylov Y. On the Lambek Invariants of Commutative Squares in a Quasi-Abelian Category. Sci. Ser. A Math. Sci. (N.S.) [Internet]. 2005 Jan. 15 [cited 2025 Jun. 7];11:57-6. Available from: https://revistas.usm.cl/scientia/article/view/73