00567naa#a2200169#i#450# EN\\bibl\123087 20260522104145.5 3034-4689 20260508b2026####ek#y0engy0150####ca RU APPLICATION OF ISOGEOMETRIC APPROXIMATION BY CUBIC SPLINES IN THE CALCULATION OF THREE-DIMENSIONAL STRUCTURES BY THE VARIATIONAL METHOD Journal article Kazan Kazan National Research Technological University 2026 4 с. Journal article local Sahbiev O. M. vestniktu.ru