Language access redirects research toward underused national sources

Which languages would most expand access to naval-history sources?

Japanese and Russian would be especially valuable, followed by French, Italian, and Portuguese for access to additional national sources.

Language is a practical limit on which naval histories a researcher can investigate directly. Japanese and Russian come first because English-language work already makes American and British subjects comparatively accessible. French and Italian would open two more major European traditions with substantial primary and secondary literature. Portuguese would add both Portugal and Brazil, so the value of a language lies partly in how many distinct national archives and historiographies it unlocks.