Redchuk, I. K., and A. V. Roiter. “Singular Locally Scalar Representations of Quivers in Hilbert Spaces and Separating Functions”. Ukrains’kyi Matematychnyi Zhurnal 56, no. 6 (June 25, 2004): 796–809. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/3799.