Alguacil, F. J. “Study of the Structure of H2SO4-Amine Primene 81R and Fe(III)-Amine Primene 81R Sulphate Compounds by Infrared Spectroscopy”. Revista De Metalurgia, vol. 35, no. 4, Aug. 1999, pp. 249-54, doi:10.3989/revmetalm.1999.v35.i4.631.