2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/78265An enumeration is given of certain equivalence classes of directed multigraphs having 0 to 5 nodes with each node having 2 incoming and 2 outgoing arcs.PDF file, 14 pages, 123 figures. Figures clarified, typos related to Classes 4,22,6 and 4,23,96 fixedCombinatoricstext