Caetano, Paulo Sá, Mafalda Luísa de Almeida Serra Patuleia, and Margarida Isabel Moreira Ferreira. 2012. “ABOVE AND UNDER GROUND: A PROPOSAL FOR URBAN GEOTOURISTIC TOURS IN LISBON”. Tourism & Management Studies, January, 426-37. https://www.tmstudies.net/index.php/ectms/article/view/207.