@article{GDZPPN00249020X,
title = {Commutativity of Operators on the Lattice of Existence Varieties.},
journal = {Monatshefte f\"ur Mathematik},
volume = {123},
year = {1997},
pages = {337-364},
zbl = {0870.20042},
url = {http://dml.mathdoc.fr/item/GDZPPN00249020X}
}
Reilly, Norman R.; Zhang, Shuhua. Commutativity of Operators on the Lattice of Existence Varieties.. Monatshefte für Mathematik, Tome 123 (1997) pp. 337-364. http://gdmltest.u-ga.fr/item/GDZPPN00249020X/