Giacomo Lenzi. A positive set theory with equality revisited. Mathematical Structures in Computer Science, 18(1):177-188, 2008. [doi]
@article{Lenzi08,
title = {A positive set theory with equality revisited},
author = {Giacomo Lenzi},
year = {2008},
doi = {10.1017/S0960129508006610},
url = {http://dx.doi.org/10.1017/S0960129508006610},
researchr = {https://researchr.org/publication/Lenzi08},
cites = {0},
citedby = {0},
journal = {Mathematical Structures in Computer Science},
volume = {18},
number = {1},
pages = {177-188},
}