Anyone know where to find this book. Its called Za...... (cant remember the name). I need it to make some kind of great weapon or something

In Umar hills you need to talk to one of the guys outside the Inn and ask to see his stuff for sale and then that is where you get the book...it is the first book listen in his inventory....named Za??????. After you purchase this book the game will take you to the riddle mode and you will have to answer the riddle on the tanners letter. Good Luck!!! Plan to save before speaking to this guy because if you get the riddle wrong you will have to reload and try again. I have the answer but I'll let you try first. If needed post requesting info

The book is called "The history of the Zentarim"