Erich Grädel, Martin Otto, Eric Rosen. Undecidability results on two-variable logics. Arch. Math. Log., 38(4-5):313-354, 1999. [doi]
@article{GradelOR99,
title = {Undecidability results on two-variable logics},
author = {Erich Grädel and Martin Otto and Eric Rosen},
year = {1999},
doi = {10.1007/s001530050130},
url = {http://dx.doi.org/10.1007/s001530050130},
tags = {logic},
researchr = {https://researchr.org/publication/GradelOR99},
cites = {0},
citedby = {0},
journal = {Arch. Math. Log.},
volume = {38},
number = {4-5},
pages = {313-354},
}