The most important and trustworthy source is Cronica conflictus Wladislai regis Poloniae cum Cruciferis anno Christi 1410, which was written within a year of the battle by an eyewitness.[14] Its authorship is uncertain, but several candidates have been proposed: Polish deputy chancellor Mikołaj Trąba and Władysław II Jagiełło's secretary Zbigniew Oleśnicki.[15] While the original Cronica conflictus did not survive, a short summary from the 16th century has been preserved. Another important source is Historiae Polonicae by Polish historian Jan Długosz (1415–1480).[15] It is a comprehensive and detailed account written several decades after the battle. The reliability of this source suffers not only from the long gap between the events and the chronicle, but also Długosz's alleged biases against the Lithuanians.[16] Banderia Prutenorum is a mid-15th-century manuscript with images and Latin descriptions of the Teutonic battle flags captured during the battle and displayed in Wawel Cathedral and Vilnius Cathedral.