In my last save file, I got 19 before beating the game. :/ And I deleted that save file during the confusion of the gysahl green. lol
In my current game, I got 6 of them at the Nideen village where Leonardo asks us to retrieve Pandemonium from Gilgamesh.
Going forward, I will take note of where I found each one of them. It won't be quick as my job is quite demanding these days. ^^"