Sejm in Piotrków in winter. 1510.
The sejm was called on 13 November 1509 to be held on 25 January 1510. The pre-sejm sejmiks were held in January of 1510. The proceedings began not until 5 February and lasted till 2 March 1510.
See: Z. Wojciechowski, Zygmunt Stary [Sigismund I the Old], Warszawa 1946. Ustawodawstwo zob. Volumina Constitutionum, T. 1, cz. 1, Design and layout prepared by S. Grodziski, I. Dwornicka, W. Uruszczak, Warszawa 1996, s. 222-237.