Heybroek, H.M. (1993). "The Dutch Elm Breeding Program". In Sticklen, Mariam B.; Sherald, James L. (eds.). Dutch Elm Disease Research. New York, USA: Springer-Verlag. pp. 16–25. ISBN978-1-4615-6874-2. Retrieved 26 October 2017..
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.
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The thicker branches have a slight sinusoid form compared to ‘Vegeta’, with straight branches.
Photograph of 'Commelin' elm
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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.