People visit the Lisbon Book Fair 2020 in Lisbon, Portugal, on Aug. 27, 2020. The 90th edition of the Lisbon Book Fair, originally scheduled for May/June, kicked off on Aug. 27 due to the COVID-19 pandemic. (Photo by Pedro Fiuza/Xinhua)

People visit the Lisbon Book Fair 2020 in Lisbon, Portugal, on Aug. 27, 2020. The 90th edition of the Lisbon Book Fair, originally scheduled for May/June, kicked off on Aug. 27 due to the COVID-19 pandemic. (Photo by Pedro Fiuza/Xinhua)

People visit the Lisbon Book Fair 2020 in Lisbon, Portugal, on Aug. 27, 2020. The 90th edition of the Lisbon Book Fair, originally scheduled for May/June, kicked off on Aug. 27 due to the COVID-19 pandemic. (Photo by Pedro Fiuza/Xinhua)

Portuguese President Marcelo Rebelo de Sousa delivers a speech on the opening ceremony of the Lisbon Book Fair 2020 in Lisbon, Portugal, on Aug. 27, 2020. The 90th edition of the Lisbon Book Fair, originally scheduled for May/June, kicked off on Aug. 27 due to the COVID-19 pandemic. (Photo by Pedro Fiuza/Xinhua)

Photo taken on Aug. 27, 2020 shows a general view of the Lisbon Book Fair 2020 in Lisbon, Portugal. The 90th edition of the Lisbon Book Fair, originally scheduled for May/June, kicked off on Aug. 27 due to the COVID-19 pandemic. (Photo by Pedro Fiuza/Xinhua)