- G. P. H. Chorley, “The Agricultural Revolution in Northern Europe, 1750-1880: Nitrogen, Legumes, and Crop Productivity.” The Economic History Review, vol. 34, no. 1, 1981, pp. 71–93. JSTOR, www.jstor.org/stable/2594840. Accessed 4 Jan. 2021.
- T. Kjaergaard, A plant that changed the world: The rise and fall of clover, 1000 – 2000, online resource
- Baude, M., Kunin, W., Boatman, N. et al. Historical nectar assessment reveals the fall and rise of floral resources in Britain. Nature 530,85–88 (2016)
See full list of Individual Species References.