Analysis of information sources in references of the Wikipedia article "Jack Russell Terrier" in German language version.
“In the first place, the colour is white with just a patch of dark tan over each eye and ear, while a similar dot, not larger than a penny piece, marks the root of the tail. The coat, wich is thick, close, and a trifle wiry, is well calculated to protect the body from wet and cold, but has no affinity with the long, rough jacket of a Scotch terrier. The legs are straight as arrows, the feet perfect; the loins and conformation of the whole frame indicative of hardihood and endurance; while the size and height of the animal may be compared to that of a full-grown vixen fox.”
siehe J. Russell: A memoir of the Rev. John Russell and his out-of-door life. (PDF (18,8MB)) 1902, S. 34, abgerufen am 22. Januar 2011 (englisch).