Reddit mentions of Sudoku Puzzle Game Book Volume 1: 200 Puzzles

I've asked about the book here: Can anyone identify this book?

[edit: The OP answered that, giving the Amazon India reference. I found it on the U.S. site: Sudoku Puzzle Game Book Volume 1: 200 Puzzles by Chandra Singh. The US publication date is 2015, shipped by Amazon (which means they have it in stock), whereas the India listing has a 2016 publication date, and is from a books-on-demand publisher. It is entirely possible that the 2016 edition has been fixed. There are no comments in either place pointing out multiple solutions.]

And I also issued a challenge. I cracked this puzzle, but not the second. I had a conversation on Quora recently with a "puzzle personality" where he claimed that improper sudoku (those without a single and unique solution) were not "puzzles" because they cannot be solved. Well, it took me an hour, but I solved this puzzle, providing a pattern of numbers that satisfied the original and clear stated rules and then showing three more solutions (out of very many). Later, sudoku with multiple solutions were called "improper," which is a technical term. An improper sudoku is still a sudoku.

Ordinary methods will not do the trick, but Ariadne's Thread can, specifically the form recommended by Mepham in The Book of Sudoku 3 (2005) (which is Binary AT, with recursion). It can be done without guessing, just following a clear and reliable algorithm that will always work. I now think I could do it in about half that time. I will describe the technique in more detail on request. Very simple, very fast, far faster than people have claimed for AT.

To me, there is satisfaction in being able to solve any Sudoku, never being "stuck," knowing what to do to find solutions, developing process and making it efficient, and then, in explaining it such that at least one person gets it.