To add to the confusion- There are several compositions called "Viking Song."

"Viking Song," Nick Allmark. About the Greenland colony failure.
http://www.nickallmark.co.uk/page6/page8/page8.html

Brian A. Hartford, "A Viking Song."
http:www.authorsden.com/visit/viewPoetry.asp?id=170897

Beth Wheeler, "Viking Song," tune Jingle Bells
http://www.chimeracorner.com/beth/viking.html

S. Coleridge Taylor, "Viking Song." Sheet music published. I have not checked for the composer of the music.

More on google.

Except for the Mudcat reference, I could not find the Martin and dello Joio song on google.