you won't find them ;)

The names of languages in DNN come directly from ASP.NET (and from Windows), see here for more info: http://msdn2.microsoft.com/en-us/library/system.globalization.cultureinfo.aspx

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there is an interference between common fallback mechanisms and DNN fallback chain, because of the different scenarios of DNN localization, in order to cover additional situations, which needs various evaluations:

• determing the language to display from user settings,  browser settings, portal default and determine the resource file
• which base file to retrieve the key from (resx assotiated with the ascx, the module or a global one)
• and as well to use from portal specific modification, host modification and default resources.