Analysis of information sources in references of the Wikipedia article "Mamíferos mariños" in Galician language version.
Using marine mammals for military purposes isn't restricted to Russia—the U.S. Navy has had a similar program since the 1960s (O uso de mamíferos mariños con propósitos militares non está restrinxido a Rusia; a Mariña dos EUA ten un programa similar desde a década de 1960)