The first account of the De Soto expedition to appear in print was the Relecam verdadeira dos trabalhos q ho governador do Fernado de souto e certos fidalgos portugueses passarom no descobrimeto da provincia da Frolida, Agora novamete feita per hu fidalgo de Elvas, which was published in Evora, Portugal in 1557.
Boyd, Mark F.
"The Arrival of De Soto’s Expedition in Florida,"
Florida Historical Quarterly: Vol. 16
, Article 7.
Available at: https://stars.library.ucf.edu/fhq/vol16/iss3/7