Roca, A., C. Cabrera, M. L. Lorenzo, and M. C. López. “Levels of Calcium, Magnesium, Manganese, Zinc, Selenium and Chromium in Olive Oils Produced in Andalusi”. Grasas Y Aceites, vol. 51, no. 6, Dec. 2000, pp. 393-9, doi:10.3989/gya.2000.v51.i6.455.