29398 Manuel Bodirsky: Graph homomorphisms and universal algebra. Internet 2021, 89p. 29397 Peter Cameron: Graph homomorphisms. Internet 2006, 7p. 29396 Gena Hahn/Claude Tardif: Graph homomorphisms - structure and symmetry. Internet 1997, 60p. 29395 Stephen Hedetniemi: Homomorphisms of graphs and automata. TR 03105-44-T Univ. Michigan 1966, 88p. P. Hell/J. Nesetril: Graphs and homomorphisms. Oxford UP 2004.