Well, I already try to put in order depending of color of the book, it was my first guess even before getting the first code, but it didn't work. So i've tried different variation, or idea but still didn't works.
To me we have these 4 numbers, 0 (blue), 7 (red), 5 (green), and 33 (yellow) wich could also be 27 because it looks like 3 exposant 3.
On bookshelf we have blue blue, red red yellow red, green. So it should be to me : 0 0 7 7 33 (or 27), 7 ,5.
I've also tried with 3 alone, I have even tried with taking in consideration the I i C (wich does "1") cause the paper with symbole is beetween yellow and red books.
So i'm still stuck, and i don't know why. Either i don't understand how you represent the order with books, either i don't understand the yellow number.