Atabekian, V. S. “SPACES WITH LIMIT OPERATION”. Proceedings of the YSU A: Physical and Mathematical Sciences 39, no. 2 (207) (June 10, 2005): 5–10. Accessed November 23, 2024. https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol39_no2_2005_pp005-010.