O‘Hallorans, J. M., M. A. Muñoz, and P. E. Marquez. “Chicken Manure As an Amendment to Correct Soil Acidity and Fertility”. The Journal of Agriculture of the University of Puerto Rico, vol. 81, no. 1-2, Apr. 1997, pp. 1-8, doi:10.46429/jaupr.v81i1-2.3669.