1911 photograph of the great elm at Magdalen College, fallen: Maxwell, Herbert, Trees: a Woodland Notebook, Containing Observations on Certain British and Exotic Trees (Glasgow, 1915), p.55: gutenberg.org [1]
Burdekin, D.A.; Rushforth, K.D. (November 1996). "Elms resistant to Dutch elm disease"(PDF). Arboriculture Research Note. 2/96. Revised by J.F. Webber. Alice Holt Lodge, Farnham: Arboricultural Advisory & Information Service: 1–9. ISSN1362-5128. Retrieved 26 October 2017.
U. x hollandica hybrids (to judge by branching, perhaps not 'Huntingdon' clones), Burloes, near Royston, Hertfordshire, Das Ulmen Büro 'Elm of the Year, 2004', Dr. Gordon Mackenthun [2]
wikimedia.org
commons.wikimedia.org
Katalog(PDF). Vol. 108. Berlin, Germany: L. Späth Baumschulenweg. 1902–1903. pp. 132–133.
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Burdekin, D.A.; Rushforth, K.D. (November 1996). "Elms resistant to Dutch elm disease"(PDF). Arboriculture Research Note. 2/96. Revised by J.F. Webber. Alice Holt Lodge, Farnham: Arboricultural Advisory & Information Service: 1–9. ISSN1362-5128. Retrieved 26 October 2017.