Reference:
Macdonald, A. , Poulton, P. , Clark, I. , Scott, T. , Glendining, M. , Perryman, S. , Storkey, J. , Bell, J. , Shield, I. , McMillan, V. and Hawkins, J. (2018 - reprinted 2019) Rothamsted Long-term Experiments in : Guide to the Classical and other Long-term experiments, Datasets and Sample Archive - pp -1 - 58