Avdzhieva, A., and G. Nikolov. “ASYMPTOTICALLY OPTIMAL QUADRATURE FORMULAE IN CERTAIN SOBOLEV CLASSES”. Ann. Sofia Univ. Fac. Math. And Inf., vol. 102, Dec. 2015, pp. 145-69, https://stipendii.uni-sofia.bg/index.php/fmi/article/view/68.