DudkinM. Y. (2004) “Point spectrum of the schrödinger operator with point interactions at the vertices of regular <em class="a-plus-plus">N</em&gt;-gons”, Ukrains’kyi Matematychnyi Zhurnal, 56(8), pp. 1128–1134. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/3827 (Accessed: 22November2024).