Zamkovoy, Simeon, and Vassil Tzanov. 2011. “NON-EXISTENCE OF FLAT PARACONTACT METRIC STRUCTURES IN DIMENSION GREATER THAN OR EQUAL TO FIVE”. Ann. Sofia Univ. Fac. Math. And Inf. 100 (December):27-34. https://ftl5.uni-sofia.bg./index.php/fmi/article/view/244.