Yury Kovalev. Connections the Sobolev spaces and the Hilbert space ℓ2 and their application at point interaction model . Ukr. Mat. Zhurn. [Internet]. 2023Jul.19 [cited 2024May17];69(12):1615-24. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/6012