00554naa#a2200181#i#450# EN\\bibl\12242 /en/manage/index 20241117170221.7 1992-5980 20160621b2016####ek#y0engy0150####ca RUS RU Solving eigenvalues problems for Helmholtz equation by point-source method Journal article rostov on don Don state technical University 2016 8 с. Journal article local Shcherbakova Elena test.editorum.ru /en/manage/index