Voogt, G. D. (1907). Our domestic animals, their habits, intelligence and usefulness. Boston, Massachusetts: Ginn & Co.
Source: Nelson, E. W. (1918, May). Smaller mammals of North America. The National Geographic Magazine, pp. 391-493
The following are from a two page spread in the June 1920 issue of House and Garden:
Compton, H. (1904). The twentieth century dog, sporting. London: Grant Richards.
