I want to add in this post some titles of books and articles necessary for historian of working terriers breeding in their homeland.
1. Dr John Caius, Of Englishe Dogges: The Diuersities, the Names, the Natures, and the Properties, London 1576, translated into English by Abraham Fleming. The work was originally published in Latin in 1570 as Johannes Caius, De Canibus Britannicis.
2. Captain Jocelyn Lucas, The Sealyham Terrier, T.H.Crumbie Ltd, Halford Street, Leister UK 1922, Badger Digging, p. 69.
3. Ernest Leal, The Badger, Penguin Books Ltd New Naturalist Monograph series 1948, Chapter XII, Badger Sets and Life Underground, p. 146-148
4. Colonel E. D. Malcolm C. B. of Poltalloch, The West Higland White Terrier Cassell's New Book of the Dog, by Robert Leighton assisted by eminent authorities on the various breeds published by The Waverley Book Co Ltd vol. III, chapter XLI, p. 391.
Also published in 2015 as The Historical Function of Terriers by Jane Harvey in the ,,Official publication of the Terrier Club of America" 2015, issue 2, p. 36-37.