Big Suguru Book - 400 Hard to Master Puzzles 9x9 vol.2

Suguru, also known as Tectonics or Number Blocks, is a Japanese puzzle invented by Naoki Inaba. The goal is to fill a given rectangular grid with numbers, so that every designated area contains a sequence of non-repeating, consecutive numbers, starting from 1 and going up. Also, adjacent (touching) cells should not contain the same number, even diagonally.