First quarter, 2021, Herman Adèr, Paperback
SUDOKU QUARTERLY of the first quarter of 2021 contains the thirteen issues of SUDOKU WEEKLY of week 1 to week 13. Each week, there is a Sudoku for each day. All these Sudokus are magic: From Monday (which has only one magic block) until Saturday (with six magic blocks) each weekday has one more magic block than the previous day. On Sunday all blocks are magic.