3 literature references:

Author:
Year: 2005
Title:
Source: website, AOU Check-List (07-2005)
Author: Cicero, Carla
Year: 2000
Title: Oak Titmouse (Baeolophus inornatus) and Juniper Titmouse (Baeolophus ridgwayi)
Source: The Birds of North America, no. 485
Author: Gill, Frank, and Minturn Wright
Year: 2006
Title:
Source: Birds of the World: Recommended English Names