Florencio G. Asenjo. Relations irreducible to classes. Notre Dame Journal of Formal Logic, 4(3):193-200, 1963. [doi]
@article{Asenjo63,
title = {Relations irreducible to classes},
author = {Florencio G. Asenjo},
year = {1963},
doi = {10.1305/ndjfl/1093957576},
url = {http://dx.doi.org/10.1305/ndjfl/1093957576},
researchr = {https://researchr.org/publication/Asenjo63},
cites = {0},
citedby = {0},
journal = {Notre Dame Journal of Formal Logic},
volume = {4},
number = {3},
pages = {193-200},
}