4 literature references for Loxia curvirostra sitkensis Grinnell, 1909:

Year: 1996
Source: database, NODC Taxonomic Code
Author: Paynter, Raymond A. Jr., ed.
Year: 1968
Source: Check-list of Birds of the World, vol. 14
Author: American Ornithologists' Union
Year: 1957
Source: Check-list of North American Birds, 5th Edition
Author: Payne, R. B.
Year: 1987
Title: Populations and type specimens of a nomadic bird: comments on the North American Crossbills Loxia pusilla Gloger 1834 and Crucirostra minor Brehm 1845
Source: Occasional Papers of the Museum of Zoology University of Michigan, no. 714