Congruences and Hoehnke radicals on graphs. - Izak Broere; Johannes Heidema; Stefan Veldsman (Discuss. Math. Graph Theory, 2020)

Congruences and subdirect representations of graphs. - Stefan Veldsman (Electron. J. Graph Theory Appl., 2020)

A radical theory for graphs that do not admit loops. - Stefan Veldsman (Period. Math. Hung., 2023)