Marques, João Pedro, The Sounds of Silence- Nineteenth-century Portugal and the Abolition of the Salve Trade.
https://www.cepese.pt/portal%26quot%3B%26amp%26quot%26quot%26quot/pt/publicacoes/obras/volume-7-number-2-winter-2009/artigos/marques-joao-pedro-the-sounds-of-silence-nineteenth-century-portugal-and-the-abolition-of-the-salve-trade/view
https://www.cepese.pt/portal%26quot%3B%26amp%26quot%26quot%26quot/@@site-logo/CEPESE+home.png
Marques, João Pedro, The Sounds of Silence- Nineteenth-century Portugal and the Abolition of the Salve Trade.