... we banked around until we found a rainbow in the dark. It was on this occasion that I discovered that Granuaile had never heard of Ronnie James Dio. My shock at this news was such that I almost completely missed the fact that we were traveling on Bifrost, the rainbow bridge to Asgard.
Kevin Hearne (2014). “The Iron Druid Chronicles 6-Book Bundle: Hounded, Hexed, Hammered, Tricked, Trapped, Hunted”, p.1504, Del Rey