Pliuškevičius , Regimantas, and Aida Pliuškevičienė. “A Method of Marks and Indices for Linear Modal Logic”. Lietuvos matematikos rinkinys 50, no. proc. LMS (December 20, 2009): 269–274. Accessed July 17, 2024. https://www.journals.vu.lt/LMR/article/view/17976.