For 2018, the Vikings have following referees available:

National Level
Daniel Triebsch / Nico Piveteau
Maddy Hazelton / Bella Anastasiou

Regional Level
Luke Ireland / Jack Gallagher
Todd Anderson / Harry Ireland

Local Level
Miguel Aizpuru / Cassius Papera

Handball Rules
Rules of the game (here as a pdf)
Simplified Handball rules for beginners (here as a pdf)
Handball rules wonderfully explained in a short youtube clip (here)