North to Alaska

This song has two different ISWC's and three different composers, and I don't know exactly what's going on...
Did Mike Phillips only write the lyrics, or the music? Did Johnny Horton and Ben Tillman just compose the music but not the lyrics?
Wikipedia says two different things, and the BMI Songview Catalog says two different things. (The ISWC lookup at CIASC is currently down.)