"To determine the point cost of a Contact Group, select its effective skill, frequency of appearance, and reliability level just as you would for a simple Contact, then multiply the resulting cost by 5." (Basic Set 44)
Referenced in GURPS Dungeon Fantasy 9: Summoners™, p. 18, which adds the specialization Contact Group (Local Spirits).
- On replacing Contact Group with Rank in GURPS Action 
- On high effective skill levels, and whether Contact Group or Allies is suitable for a character 
- On a Contact Group actually being an individual , 
- On its geographic coverage