Von Ludwig, C. F. H. “List of Exotic Trees, Shrubs, Plants, Bulbs; Garden Flower, Forest, and Other Seeds: Imported Lately from Germany (Wurtemberg and Hamburg), Holland, &c. By the Danish Ship Norden, Capt. Burd, and the Ionia, Capt. C. Buck”. South African Quarterly Journal, vol. 1, no. 5, Oct. 1831, pp. 40-45, https://doi.org/10.21504/saqj.15.2598.