Arlinskii, Yu. M., and S. Hassi. “Representations of Closed Quadratic Forms Associated With Stieltjes and Inverse Stieltjes Holomorphic Families of Linear Relations”. Methods of Functional Analysis and Topology, vol. 27, no. 2, June 2021, pp. 103-29, https://doi.org/https://doi.org/10.31392/MFAT-npu26_2.2021.01.