"AGM Plants - Ornamental"(PDF). Royal Horticultural Society. July 2017. p. 107. Archived(PDF) from the original on 3 May 2020. Retrieved 17 February 2019.
"AGM Plants - Ornamental"(PDF). Royal Horticultural Society. July 2017. p. 107. Archived(PDF) from the original on 3 May 2020. Retrieved 17 February 2019.