Louzeiro, H. C., Soledade, L. E. B., de Souza, A. G., Maciel, A. P., & Silva, F. C. (2015). Free glycerin determination in ethanol biodiesel utilizing spectrophotometric and chromatographic (GC/FID) methods. Eclética Química, 38(1), 25–36. https://doi.org/10.26850/1678-4618eqj.v38.1.2013.p25-36