Melvin Fitting. Tableau methods of proof for modal logics. Notre Dame Journal of Formal Logic, 13(2):237-247, 1972. [doi]
@article{Fitting72,
title = {Tableau methods of proof for modal logics},
author = {Melvin Fitting},
year = {1972},
doi = {10.1305/ndjfl/1093894722},
url = {http://dx.doi.org/10.1305/ndjfl/1093894722},
researchr = {https://researchr.org/publication/Fitting72},
cites = {0},
citedby = {0},
journal = {Notre Dame Journal of Formal Logic},
volume = {13},
number = {2},
pages = {237-247},
}