@article{1093891883,
author = {Purtill, Richard L.},
title = {Paradox-free deontic logics.},
journal = {Notre Dame J. Formal Logic},
volume = {16},
number = {1},
year = {1975},
pages = { 483-490},
language = {en},
url = {http://dml.mathdoc.fr/item/1093891883}
}
Purtill, Richard L. Paradox-free deontic logics.. Notre Dame J. Formal Logic, Tome 16 (1975) no. 1, pp. 483-490. http://gdmltest.u-ga.fr/item/1093891883/