RIVAS PARDO, Pablo. Maritime Piracy and its Characterization as a Threat: Presence, Type, Arms, Violence, and Ships under Attack between 1991 and 2019. rev.relac.int.estrateg.segur. [online]. 2021, vol.16, n.1, pp.153-175.  Epub 07-Mayo-2021. ISSN 1909-3063.