Book of Enoch (1 Enoch) 75:1
And the leaders of the heads of the thousands, who are placed over the whole creation and over all the stars, have also to do with the four intercalary days, being inseparable from their office, according to the reckoning of the year, and these render service on the four days which are not reckoned in the reckoning of the year.
Background and history of Book of Enoch (1 Enoch), and issues with this book.
R. H. Charles, The Book of Enoch (London: SPCK, 1917), public domain. The verse text is the English Wikisource transcription of that translation. Charles’s editorial signs are kept. He rearranges some verses in chapters 5, 39, 90, 91, and 106, so those chapters are not a straight 1, 2, 3 sequence.