Andrei S. Morozov, Margarita V. Korovina. On sigma-definability without equality over the real numbers. Math. Log. Q., 54(5):535-544, 2008. [doi]
@article{MorozovK08,
title = {On sigma-definability without equality over the real numbers},
author = {Andrei S. Morozov and Margarita V. Korovina},
year = {2008},
doi = {10.1002/malq.200710064},
url = {http://dx.doi.org/10.1002/malq.200710064},
researchr = {https://researchr.org/publication/MorozovK08},
cites = {0},
citedby = {0},
journal = {Math. Log. Q.},
volume = {54},
number = {5},
pages = {535-544},
}