Melvin Fitting. A modal logic ε-calculus. Notre Dame Journal of Formal Logic, 16(1):1-16, 1975. [doi]
@article{Fitting75, title = {A modal logic ε-calculus}, author = {Melvin Fitting}, year = {1975}, doi = {10.1305/ndjfl/1093891609}, url = {http://dx.doi.org/10.1305/ndjfl/1093891609}, researchr = {https://researchr.org/publication/Fitting75}, cites = {0}, citedby = {0}, journal = {Notre Dame Journal of Formal Logic}, volume = {16}, number = {1}, pages = {1-16}, }