How to use a common method across all projects without having to pass the namespaces

I am working on localization of texts across all the 5 projects which together forms the product.

Localization: So If user is from USA, they will see the product in en-US, if they are from China they will see the text in ch-CH.

And I am stuck at below stuff.

Each project will have its OWN bucket of Resx file (file where I am keeping for translations).

Project A - A.en-US.resx file
            A.cn-CH.resx file
Project B - B.en-US.resx file
            B.ch-CH.resx file
.
.
.

Now I have a Project Common which gets referenced by all the projects. So What I wrote a singleton class in Common

public sealed class Translation 
{
    private static readonly Translation translation = new Translation();

    public static Translation GetTranslation { get { return translation; } }
    private Translation() { }
    static Translation() { }

    public string GetTranslatedMessage(string key, CultureInfo culture, string message, string namespace)
    {
            var rm = new ResourceManager("namespace", Assembly.GetExecutingAssembly());
            message = rm.GetString(key, culture);
            return message;
    }
}

So far so good, As you can see I am using namespace as 4th parameter with resource manager so that I can look for the translation in the right project bucket , I just do something like below:

Translation.Translate(key, culture, message, namespace) // singleton class taking in the namespace to find the right bucket

And it works fine.

Question/Problem: But from every project I need to pass the namespace, I mean where ever I call I need to pass the namespace. I am wondering is there any way, I can implicitly tell which bucket each project needs to look into. Can I use Abstract or 2 singleton classes, factory may be?, or something like that. I am newbie so I am not familiar on how to tackle this issue. I just don't want to pass namespace in every call.