Craig Williams 
Annotated Sudoku [EPUB ebook] 
Using Sudoglyphicstm…The Notably Better Way to Solve.

The Annotated Sudoku uses a simple marking system called Sudoglyphics, which builds a path for beginning, experienced, and expert solvers to discover the joy of successfully taking on even the most difficult puzzles and completing them faster than they might have thought possible. The method specifically records and updates the status of every possible answer that remains after an analysis has been performed. The constant marking keeps the solver more engaged between answers. Meanwhile, the accumulation of these marks build visual patterns that otherwise must be created and juggled in memory until they are needed to restart solving where others will most likely get stuck. Included in the book is a step-by-step illustrated explanation for solving a complete, expert-level puzzle using the simple tools and strategies discussed. Regardless of your experience, you can learn to take on the sudoku challenge at the highest level and perform faster without needlessly taxing your memory or backtracking.