(1)
Kamprath, E. J.; Beegle, D. B.; Fixen, P. E.; Hodges, S. C.; Joern, B. C.; Mallarino, A. P.; Miller, R. O.; Sims, J. T.; Ward, R.; Wolf, A. M. Relevance Of Soil Testing To Agriculture And The Environment. CAST Publications 2000. https://doi.org/10.62300/q6wd7414.