Saranyana, J.I. (Josep Ignasi). "Filosofando sobre el valor del dinero en la España de Felipe II". En . , 1997,
Fr. Tomás de Mercado, O.P., and Fr. Bartolomé Frías de Albornoz, Spanish economists of the era of Philip II (later half of 16* century) proposed monetary theories, they were the real pioneers in what has become some of the most outstanding modera monetary theories. Mercado suggested some ideas on "welfare economy". Frías put foward the "quantity ecuation", formulated by the "classical economists", two centuries later.