Here at LAPOM we are keep adding Mahjong Tactics books from Japan.
And we are building library to study.
We also think just reading is not helping. The most important part is understanding and make affect in your game. Reading and learning is one of the way to study, and we also recommend watch other games including videos, think, discuss, reviewing the game and more.
We don't know what will fit for you to catching faster, but we kept doing this past couple years, and we think level of the game and understanding is getting deeper.