M. Campelo, R. Lima, and C. Sales.
" Complexity of the Girth Problem on Arc-colored Digraphs", in <em>Anais do XI Encontro de Teoria da Computação</em>, Gramado/RS, 2026, pp. 90-94, doi: <a href="https://doi.org/10.5753/etc.2026.23502">https://doi.org/10.5753/etc.2026.23502</a>.