9b11f552____Final_Fantasy_X_2_Item_List__Location
[Name] Book of Magical Dances I [Description] Enables Songstress to learn MP Mambo. [Location] 
Obtained after finding all ten Crimson Spheres and unlocking the Den of Woe in Mushroom Rock Road during Chapter 5 and defeating all the bosses there.
Final Fantasy World - Final Fantasy X-2 Item List
Location