Thoralf Skolem. Investigations on a comprehension axiom without negation in the defining propositional functions. Notre Dame Journal of Formal Logic, 1(1-2):13-22, 1960. [doi]
@article{Skolem60,
title = {Investigations on a comprehension axiom without negation in the defining propositional functions},
author = {Thoralf Skolem},
year = {1960},
doi = {10.1305/ndjfl/1093956425},
url = {http://dx.doi.org/10.1305/ndjfl/1093956425},
researchr = {https://researchr.org/publication/Skolem60},
cites = {0},
citedby = {0},
journal = {Notre Dame Journal of Formal Logic},
volume = {1},
number = {1-2},
pages = {13-22},
}