The chants used for this recording are taken from the 1961 Liber Usualis. These differ slightly from the 2003 Leduc edition of the piece. The registration and keyboards used also differ slightly and reflect the appearance of main chants and their 'fragments'. A footnote in the score (J.A. or M-C.A?) asks the player to 'engineer' that the notes of the plainchant do not fall at the same time as the accompanying 'berceuse'. The chant should give (donnent) the movement (not easy!).