Conversion Histories

There's nowhere good to post this, so it might as well be here.

I'm looking for a good history specifically about the Christianization of the Vikings. Also, if possible, I'd also be interested in similar books each focused on the conversion of the other peoples of Northern Europe, i.e. Celts, Goths, Franks, etc. I'd prefer the work to be as comprehensive as possible, so I'm not looking for an general history covering conversion of the whole region, rather for individual histories full of specific details on the reception of the faith among each individual group.

Thanks much.

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