Dorothy Bollman, M. Tapia. On the recursive unsolvability of the provability of the deduction theorem in partial propositional calculi. Notre Dame Journal of Formal Logic, 13(1):124-128, 1972. [doi]
@article{BollmanT72,
title = {On the recursive unsolvability of the provability of the deduction theorem in partial propositional calculi},
author = {Dorothy Bollman and M. Tapia},
year = {1972},
doi = {10.1305/ndjfl/1093894634},
url = {http://dx.doi.org/10.1305/ndjfl/1093894634},
researchr = {https://researchr.org/publication/BollmanT72},
cites = {0},
citedby = {0},
journal = {Notre Dame Journal of Formal Logic},
volume = {13},
number = {1},
pages = {124-128},
}