Norgėla, Stanislovas, and Linas Petrauskas. “Transformations of Formulae of Hybrid Logic”. Lietuvos matematikos rinkinys 51, no. proc. LMS (December 21, 2010): 342–346. Accessed November 7, 2025. https://www.zurnalai.vu.lt/LMR/article/view/17846.