Raymond E. Jennings, D. K. Johnston, Peter K. Schotch. The n-adic first-order undefinability of the Geach formula. Notre Dame Journal of Formal Logic, 22(4):375-378, 1981. [doi]
@article{JenningsJS81,
title = {The n-adic first-order undefinability of the Geach formula},
author = {Raymond E. Jennings and D. K. Johnston and Peter K. Schotch},
year = {1981},
doi = {10.1305/ndjfl/1093883516},
url = {http://dx.doi.org/10.1305/ndjfl/1093883516},
researchr = {https://researchr.org/publication/JenningsJS81},
cites = {0},
citedby = {0},
journal = {Notre Dame Journal of Formal Logic},
volume = {22},
number = {4},
pages = {375-378},
}