1. Haggard, H.R. (1911) Rural Denmark and its Lessons, Longmans, Green and Co. (London, UK), p. 125
2. No named author (1903) Report on Co-operative Agriculture and Rural Conditions in Denmark (Miscellaneous series, Bulletin 7), Department of Agriculture and Technical Instruction for Ireland (Dublin, Republic of Ireland), p. 2 of the introduction
3. The second agricultural revolution, 1815–1880;Thompson;Economic History Review,1968
4. Bjørn, C. (1988) Det moderne landbrug grundlægges 1840–1860. In Det Danske Landbrugs Historie (Vol. 3) (Bjørn, C. et al., eds), pp. 166–192, Landbohistorisk Selskab (Odense, Denmark)
5. On the background and reception of Liebig's book see Schling-Brodersen, U. (1992) Liebig's role in the establishment of agricultural chemistry. Ambix 39, 21–31