Nathan Bowler, Thomas Forster. Normal subgroups of infinite symmetric groups, with an application to stratified set theory. Journal of Symbolic Logic, 74(1):17-26, 2009. [doi]
@article{BowlerF09,
title = {Normal subgroups of infinite symmetric groups, with an application to stratified set theory},
author = {Nathan Bowler and Thomas Forster},
year = {2009},
url = {http://projecteuclid.org/euclid.jsl/1231082300},
researchr = {https://researchr.org/publication/BowlerF09},
cites = {0},
citedby = {0},
journal = {Journal of Symbolic Logic},
volume = {74},
number = {1},
pages = {17-26},
}