Herron, Matthew D.; Castoe, Todd A.; Parkinson, Christopher L. (2004). Sciurid phylogeny and the paraphyly of Holarctic ground squirrels (Spermophilus). Molecular Phylogenetics and Evolution. 31 (3): 1015—30. doi:10.1016/j.ympev.2003.09.015. PMID15120398.
Herron, Matthew D.; Castoe, Todd A.; Parkinson, Christopher L. (2004). Sciurid phylogeny and the paraphyly of Holarctic ground squirrels (Spermophilus). Molecular Phylogenetics and Evolution. 31 (3): 1015—30. doi:10.1016/j.ympev.2003.09.015. PMID15120398.