This article comprises three brief footnotes to research into early Polish music. Although they are based on sources which are familiar and already largely investigated and described, they can still reveal some new aspects in the history of the art of music in old Poland. The first footnote 'I. Jaki ksztalt miala piesn 'Boga w swietych jego chwalmy'? Do problemu lacinsko-polskich kontrafaktur' (What was the shape of the song 'Let us Praise the Lord in His Saints'? Concerning the problem of Latin-Polish Contrafactures) concerns the issue of establishing the correct transmission of a music composition. Using a song by the polonised Italian composer, Diomedes Caton (before 1570 - after 1607), as an example, the author finds that sometimes a transmission of a vocal work, which apparently does not raise any doubts, and which is published in a contemporary source edition, has to undergo certain corrections. These corrections, by being compared to another, much later historical source, i.e., Józef Elsner's (1764-1854) 'Sumariusz moich utworów muzycznych' (Summary of my musical works), may be made optimally objective, and as a consequence may lead to a reliable recreation of the accurate shape of the work. The second part of the article 'II. Plankty z monogramem M. M.' (Dirges with the monogram M.M.) takes up the issue of identifying works signed with the monogram M.M. as those by a leading Polish composer from the early Baroque period, Marcin Mielczewski (d. 1651). The arguments and comparisons presented there lead to the conclusion that the two vocal-instrumental Polish dirges signed with the monogram M.M., 'Ach, ciezka zalosc' (Oh heavy sorrow) and 'Zemdlony Jezus' (The fainting Jesus), for two vocal parts, two violins and basso continuo, preserved in the source dated to 1714, may be identified as the work of Mielczewski. The third part of the text 'III. Autocytaty-transkrypcje' (Self-quotations - transcriptions) deals with the music of an outstanding Polish composer active during the second half of the eighteenth century in Jasna Góra, Marcin Józef Zebrowski (c. 1710- after 1780). Comparative analyses of three works by Zebrowski, the psalm 'Dixit Dominus' from the Vesperae cycle, 'Missa Pastoritia ex D and Missa Pastoralis', reveal interesting examples of relationships within the musical material. In 'Missa Pastoralis' the composer uses fragments of fugued passages from 'Missa Pastoritia' ('Cum Sancto Spiritui in gloria Dei Patris. Amen' from Gloria) and the psalm 'Dixit Dominus' (the final 'Amen'), transcribing them to a different performance apparatus while making only minimal changes. Such techniques found in the work of Zebrowski expand the set of known examples of the practice of using their own musical compositions by the Old Polish masters.