Malamud, M. M., and V. I. Mogilevskii. “Krein Type Formula for Canonical Resolvents of Dual Pairs of Linear Relations”. Methods of Functional Analysis and Topology 8, no. 4 (December 25, 2002): 72–100. Accessed December 18, 2025. https://zen.imath.kiev.ua/index.php/mfat/article/view/201.