His works on Polish history are based on minute and critical study of the documents; they were collected under the title Polska, dzieje i rzeczy jej rozpatrzywane (Poland, her History and Affairs surveyed), in 20 vols.
A cheap edition of the leading Polish classics, well adapted for dissemination among the people, has been published, under the title of Biblioteka Polska, at Cracow.
Bruckner (Leipzig, 1901; also written in Polish); Chmielowski, History of Polish Literature (in Polish, 3 vols.); Stanislaus Tarnowski, History of Polish Literature (in Polish); Grabowski, Poezya Polska po roku 1863 (Cracow, 1903); Heinrich Nitschmann, Geschichte der polnischen Literatur (Leipzig; sine anno).
Kronika polska, which was afterwards continued by his son.